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[v3,0/3] drm: Add Thine THC63LVD1024 LVDS decoder bridge

Message ID 1520951425-13843-1-git-send-email-jacopo+renesas@jmondi.org
Headers show
Series drm: Add Thine THC63LVD1024 LVDS decoder bridge | expand

Message

Jacopo Mondi March 13, 2018, 2:30 p.m. UTC 
Hello,
   opposed to v2, this version drops the "transparent LVDS decoder" and provides
support for the Thine THC63LVD1024 chip only.

I removed all references to "lvds-decoder" and made driver and bindings
specific for the above mentioned chip.

Andrzej: Bindings now describe 2 available inputs (Port@0 mandatory, Port@1
optional) and 2 possible outputs (Port@2 mandatory, Port@3 optional). The driver
still takes only Port@0 and Port@2 into account. This leaves out discussions
on how support bridges with multiple input streams within the DRM framework from
this series.

Simon: Please drop the previous bindings proposal you marked as "deferred" as
that one is superseded by this new one.

I still plan to use this series to propose an API to propagate formats through
bridges, which is not possible at the moment, if I got things right.

Thanks
   j

v2 -> v3:
- Drop support for "lvds-decoder" and make the driver THC63LVD1024 specific
-- Rework bindings to describe multiple input/output ports
-- Rename driver and remove "lvds-decoder" references
-- Rework Eagle DTS to use new bindings

v1 -> v2:
- Drop support for THC63LVD1024

Jacopo Mondi (3):
  dt-bindings: display: bridge: Document THC63LVD1024 LVDS decoder
  drm: bridge: Add thc63lvd1024 LVDS decoder driver
  arm64: dts: renesas: Add LVDS decoder to R-Car V3M Eagle

 .../bindings/display/bridge/thine,thc63lvd1024.txt |  63 ++++++
 arch/arm64/boot/dts/renesas/r8a77970-eagle.dts     |  31 ++-
 drivers/gpu/drm/bridge/Kconfig                     |  10 +
 drivers/gpu/drm/bridge/Makefile                    |   1 +
 drivers/gpu/drm/bridge/thc63lvd1024.c              | 239 +++++++++++++++++++++
 5 files changed, 342 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/display/bridge/thine,thc63lvd1024.txt
 create mode 100644 drivers/gpu/drm/bridge/thc63lvd1024.c

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Comments

Simon Horman March 13, 2018, 6:47 p.m. UTC | #1 
On Tue, Mar 13, 2018 at 03:30:25PM +0100, Jacopo Mondi wrote:
> The R-Car V3M Eagle board includes a transparent THC63LVD1024 LVDS
> decoder, connected to the on-chip LVDS encoder output on one side
> and to HDMI encoder ADV7511w on the other one.
> 
> As the decoder does not need any configuration it has been so-far
> omitted from DTS. Now that a driver is available, describe it in DT
> as well.
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>

I have marked this as deferred pending acceptance of the new binding.
Please repost or ping me once that has happened.
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Andrzej Hajda March 14, 2018, 8:42 a.m. UTC | #2 
On 13.03.2018 15:30, Jacopo Mondi wrote:
> Add DRM bridge driver for Thine THC63LVD1024 LVDS to digital parallel
> output decoder.

IMO converter suits here better, but it is just suggestion.

>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> ---
>  drivers/gpu/drm/bridge/Kconfig        |   7 +
>  drivers/gpu/drm/bridge/Makefile       |   1 +
>  drivers/gpu/drm/bridge/thc63lvd1024.c | 241 ++++++++++++++++++++++++++++++++++
>  3 files changed, 249 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/thc63lvd1024.c
>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 3b99d5a..facf6bd 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -92,6 +92,13 @@ config DRM_SII9234
>  	  It is an I2C driver, that detects connection of MHL bridge
>  	  and starts encapsulation of HDMI signal.
>  
> +config DRM_THINE_THC63LVD1024
> +	tristate "Thine THC63LVD1024 LVDS decoder bridge"
> +	depends on OF
> +	select DRM_PANEL_BRIDGE

You don't use PANEL_BRIDGE, it should be possible to drop the select.

> +	---help---
> +	  Thine THC63LVD1024 LVDS decoder bridge driver.

Decoder to what?
Maybe it would be better to say it is LVDS/parallel or LVDS/RGB
converter or bridge.

> +
>  config DRM_TOSHIBA_TC358767
>  	tristate "Toshiba TC358767 eDP bridge"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 373eb28..fd90b16 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
>  obj-$(CONFIG_DRM_SIL_SII8620) += sil-sii8620.o
>  obj-$(CONFIG_DRM_SII902X) += sii902x.o
>  obj-$(CONFIG_DRM_SII9234) += sii9234.o
> +obj-$(CONFIG_DRM_THINE_THC63LVD1024) += thc63lvd1024.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
>  obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
>  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
> diff --git a/drivers/gpu/drm/bridge/thc63lvd1024.c b/drivers/gpu/drm/bridge/thc63lvd1024.c
> new file mode 100644
> index 0000000..4b059c0
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/thc63lvd1024.c
> @@ -0,0 +1,241 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * THC63LVD1024 LVDS to parallel data DRM bridge driver.
> + *
> + * Copyright (C) 2018 Jacopo Mondi <jacopo+renesas@jmondi.org>
> + */
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_panel.h>
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/of_graph.h>
> +#include <linux/regulator/consumer.h>
> +
> +static const char * const thc63_reg_names[] = {
> +	"vcc", "lvcc", "pvcc", "cvcc", };
> +
> +struct thc63_dev {
> +	struct device *dev;
> +
> +	struct regulator *vccs[ARRAY_SIZE(thc63_reg_names)];
> +
> +	struct gpio_desc *pwdn;
> +	struct gpio_desc *oe;
> +
> +	struct drm_bridge bridge;
> +	struct drm_bridge *next;
> +};
> +
> +static inline struct thc63_dev *to_thc63(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct thc63_dev, bridge);
> +}
> +
> +static int thc63_attach(struct drm_bridge *bridge)
> +{
> +	struct thc63_dev *thc63 = to_thc63(bridge);
> +
> +	return drm_bridge_attach(bridge->encoder, thc63->next, bridge);
> +}
> +
> +static void thc63_enable(struct drm_bridge *bridge)
> +{
> +	struct thc63_dev *thc63 = to_thc63(bridge);
> +	struct regulator *vcc;
> +	unsigned int i;
> +	int ret;
> +
> +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
> +		vcc = thc63->vccs[i];
> +		if (vcc) {
> +			ret = regulator_enable(vcc);
> +			if (ret)
> +				goto error_vcc_enable;
> +		}
> +	}
> +
> +	if (thc63->pwdn)
> +		gpiod_set_value(thc63->pwdn, 0);
> +
> +	if (thc63->oe)
> +		gpiod_set_value(thc63->oe, 1);
> +
> +	return;
> +
> +error_vcc_enable:
> +	dev_err(thc63->dev, "Failed to enable regulator %u\n", i);
> +}
> +
> +static void thc63_disable(struct drm_bridge *bridge)
> +{
> +	struct thc63_dev *thc63 = to_thc63(bridge);
> +	struct regulator *vcc;
> +	unsigned int i;
> +	int ret;
> +
> +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
> +		vcc = thc63->vccs[i];
> +		if (vcc) {
> +			ret = regulator_disable(vcc);
> +			if (ret)
> +				goto error_vcc_disable;

I think in disable path you can report an error and continue - should be
safer.

> +		}
> +	}
> +
> +	if (thc63->pwdn)
> +		gpiod_set_value(thc63->pwdn, 1);
> +
> +	if (thc63->oe)
> +		gpiod_set_value(thc63->oe, 0);

Usually disable uses reverse order. Ie first disable oe, then, pwdn,
then regulators, also in reverse order.
Looks more reasonable.

> +
> +	return;
> +
> +error_vcc_disable:
> +	dev_err(thc63->dev, "Failed to disable regulator %u\n", i);
> +}
> +
> +struct drm_bridge_funcs thc63_bridge_func = {
> +	.attach	= thc63_attach,
> +	.enable = thc63_enable,
> +	.disable = thc63_disable,
> +};
> +
> +static int thc63_parse_dt(struct thc63_dev *thc63)
> +{
> +	struct device_node *thc63_out;
> +	struct device_node *remote;
> +	int ret = 0;
> +
> +	thc63_out = of_graph_get_endpoint_by_regs(thc63->dev->of_node, 2, -1);

Please define and use enums for port number, it will be more clear.

> +	if (!thc63_out) {
> +		dev_err(thc63->dev, "Missing endpoint in Port@2\n");
> +		return -ENODEV;
> +	}
> +
> +	remote = of_graph_get_remote_port_parent(thc63_out);
> +	if (!remote) {
> +		dev_err(thc63->dev, "Endpoint in Port@2 unconnected\n");
> +		ret = -ENODEV;
> +		goto error_put_out_node;
> +	}
> +
> +	if (!of_device_is_available(remote)) {
> +		dev_err(thc63->dev, "Port@2 remote endpoint is disabled\n");
> +		ret = -ENODEV;
> +		goto error_put_remote_node;
> +	}
> +
> +	thc63->next = of_drm_find_bridge(remote);
> +	if (!thc63->next)
> +		ret = -EPROBE_DEFER;
> +
> +error_put_remote_node:
> +	of_node_put(remote);
> +error_put_out_node:
> +	of_node_put(thc63_out);
> +
> +	return ret;
> +}
> +
> +static int thc63_gpio_init(struct thc63_dev *thc63)
> +{
> +	thc63->pwdn = devm_gpiod_get_optional(thc63->dev, "pwdn",
> +					      GPIOD_OUT_LOW);
Shouldn't be GPIOD_OUT_HIGH - bridge initially disabled?

Regards
Andrzej
> +	if (IS_ERR(thc63->pwdn)) {
> +		dev_err(thc63->dev, "Unable to get GPIO \"pwdn\"\n");
> +		return PTR_ERR(thc63->pwdn);
> +	}
> +
> +	thc63->oe = devm_gpiod_get_optional(thc63->dev, "oe", GPIOD_OUT_LOW);
> +	if (IS_ERR(thc63->oe)) {
> +		dev_err(thc63->dev, "Unable to get GPIO \"oe\"\n");
> +		return PTR_ERR(thc63->oe);
> +	}
> +
> +	return 0;
> +}
> +
> +static int thc63_regulator_init(struct thc63_dev *thc63)
> +{
> +	struct regulator **reg;
> +	int i;
> +
> +	reg = &thc63->vccs[0];
> +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++, reg++) {
> +		*reg = devm_regulator_get_optional(thc63->dev,
> +						   thc63_reg_names[i]);
> +		if (IS_ERR(*reg)) {
> +			if (PTR_ERR(*reg) == -EPROBE_DEFER)
> +				return -EPROBE_DEFER;
> +			*reg = NULL;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int thc63_probe(struct platform_device *pdev)
> +{
> +	struct thc63_dev *thc63;
> +	int ret;
> +
> +	thc63 = devm_kzalloc(&pdev->dev, sizeof(*thc63), GFP_KERNEL);
> +	if (!thc63)
> +		return -ENOMEM;
> +
> +	thc63->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, thc63);
> +
> +	ret = thc63_regulator_init(thc63);
> +	if (ret)
> +		return ret;
> +
> +	ret = thc63_gpio_init(thc63);
> +	if (ret)
> +		return ret;
> +
> +	ret = thc63_parse_dt(thc63);
> +	if (ret)
> +		return ret;
> +
> +	thc63->bridge.driver_private = thc63;
> +	thc63->bridge.of_node = pdev->dev.of_node;
> +	thc63->bridge.funcs = &thc63_bridge_func;
> +
> +	drm_bridge_add(&thc63->bridge);
> +
> +	return 0;
> +}
> +
> +static int thc63_remove(struct platform_device *pdev)
> +{
> +	struct thc63_dev *thc63 = platform_get_drvdata(pdev);
> +
> +	drm_bridge_remove(&thc63->bridge);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id thc63_match[] = {
> +	{ .compatible = "thine,thc63lvd1024", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, thc63_match);
> +#endif
> +
> +static struct platform_driver thc63_driver = {
> +	.probe	= thc63_probe,
> +	.remove	= thc63_remove,
> +	.driver	= {
> +		.name		= "thc63lvd1024",
> +		.of_match_table	= thc63_match,
> +	},
> +};
> +module_platform_driver(thc63_driver);
> +
> +MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
> +MODULE_DESCRIPTION("Thine THC63LVD1024 LVDS decoder DRM bridge driver");
> +MODULE_LICENSE("GPL v2");


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Jacopo Mondi March 14, 2018, 10:09 a.m. UTC | #3 
Hi Andrzej,
    thanks for review

On Wed, Mar 14, 2018 at 09:42:36AM +0100, Andrzej Hajda wrote:
> On 13.03.2018 15:30, Jacopo Mondi wrote:
> > Add DRM bridge driver for Thine THC63LVD1024 LVDS to digital parallel
> > output decoder.
>
> IMO converter suits here better, but it is just suggestion.
>
> >
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> > ---
> >  drivers/gpu/drm/bridge/Kconfig        |   7 +
> >  drivers/gpu/drm/bridge/Makefile       |   1 +
> >  drivers/gpu/drm/bridge/thc63lvd1024.c | 241 ++++++++++++++++++++++++++++++++++
> >  3 files changed, 249 insertions(+)
> >  create mode 100644 drivers/gpu/drm/bridge/thc63lvd1024.c
> >
> > diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> > index 3b99d5a..facf6bd 100644
> > --- a/drivers/gpu/drm/bridge/Kconfig
> > +++ b/drivers/gpu/drm/bridge/Kconfig
> > @@ -92,6 +92,13 @@ config DRM_SII9234
> >  	  It is an I2C driver, that detects connection of MHL bridge
> >  	  and starts encapsulation of HDMI signal.
> >
> > +config DRM_THINE_THC63LVD1024
> > +	tristate "Thine THC63LVD1024 LVDS decoder bridge"
> > +	depends on OF
> > +	select DRM_PANEL_BRIDGE
>
> You don't use PANEL_BRIDGE, it should be possible to drop the select.
>

Ack

> > +	---help---
> > +	  Thine THC63LVD1024 LVDS decoder bridge driver.
>
> Decoder to what?
> Maybe it would be better to say it is LVDS/parallel or LVDS/RGB
> converter or bridge.

"LVDS to digital CMOS/TTL parallel data converter" as the manual
describes the chip?

>
> > +
> >  config DRM_TOSHIBA_TC358767
> >  	tristate "Toshiba TC358767 eDP bridge"
> >  	depends on OF
> > diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> > index 373eb28..fd90b16 100644
> > --- a/drivers/gpu/drm/bridge/Makefile
> > +++ b/drivers/gpu/drm/bridge/Makefile
> > @@ -8,6 +8,7 @@ obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
> >  obj-$(CONFIG_DRM_SIL_SII8620) += sil-sii8620.o
> >  obj-$(CONFIG_DRM_SII902X) += sii902x.o
> >  obj-$(CONFIG_DRM_SII9234) += sii9234.o
> > +obj-$(CONFIG_DRM_THINE_THC63LVD1024) += thc63lvd1024.o
> >  obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
> >  obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
> >  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
> > diff --git a/drivers/gpu/drm/bridge/thc63lvd1024.c b/drivers/gpu/drm/bridge/thc63lvd1024.c
> > new file mode 100644
> > index 0000000..4b059c0
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/thc63lvd1024.c
> > @@ -0,0 +1,241 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * THC63LVD1024 LVDS to parallel data DRM bridge driver.
> > + *
> > + * Copyright (C) 2018 Jacopo Mondi <jacopo+renesas@jmondi.org>
> > + */
> > +
> > +#include <drm/drmP.h>
> > +#include <drm/drm_bridge.h>
> > +#include <drm/drm_panel.h>
> > +
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/of_graph.h>
> > +#include <linux/regulator/consumer.h>
> > +
> > +static const char * const thc63_reg_names[] = {
> > +	"vcc", "lvcc", "pvcc", "cvcc", };
> > +
> > +struct thc63_dev {
> > +	struct device *dev;
> > +
> > +	struct regulator *vccs[ARRAY_SIZE(thc63_reg_names)];
> > +
> > +	struct gpio_desc *pwdn;
> > +	struct gpio_desc *oe;
> > +
> > +	struct drm_bridge bridge;
> > +	struct drm_bridge *next;
> > +};
> > +
> > +static inline struct thc63_dev *to_thc63(struct drm_bridge *bridge)
> > +{
> > +	return container_of(bridge, struct thc63_dev, bridge);
> > +}
> > +
> > +static int thc63_attach(struct drm_bridge *bridge)
> > +{
> > +	struct thc63_dev *thc63 = to_thc63(bridge);
> > +
> > +	return drm_bridge_attach(bridge->encoder, thc63->next, bridge);
> > +}
> > +
> > +static void thc63_enable(struct drm_bridge *bridge)
> > +{
> > +	struct thc63_dev *thc63 = to_thc63(bridge);
> > +	struct regulator *vcc;
> > +	unsigned int i;
> > +	int ret;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
> > +		vcc = thc63->vccs[i];
> > +		if (vcc) {
> > +			ret = regulator_enable(vcc);
> > +			if (ret)
> > +				goto error_vcc_enable;
> > +		}
> > +	}
> > +
> > +	if (thc63->pwdn)
> > +		gpiod_set_value(thc63->pwdn, 0);
> > +
> > +	if (thc63->oe)
> > +		gpiod_set_value(thc63->oe, 1);
> > +
> > +	return;
> > +
> > +error_vcc_enable:
> > +	dev_err(thc63->dev, "Failed to enable regulator %u\n", i);
> > +}
> > +
> > +static void thc63_disable(struct drm_bridge *bridge)
> > +{
> > +	struct thc63_dev *thc63 = to_thc63(bridge);
> > +	struct regulator *vcc;
> > +	unsigned int i;
> > +	int ret;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
> > +		vcc = thc63->vccs[i];
> > +		if (vcc) {
> > +			ret = regulator_disable(vcc);
> > +			if (ret)
> > +				goto error_vcc_disable;
>
> I think in disable path you can report an error and continue - should be
> safer.
>

Ack

> > +		}
> > +	}
> > +
> > +	if (thc63->pwdn)
> > +		gpiod_set_value(thc63->pwdn, 1);
> > +
> > +	if (thc63->oe)
> > +		gpiod_set_value(thc63->oe, 0);
>
> Usually disable uses reverse order. Ie first disable oe, then, pwdn,
> then regulators, also in reverse order.
> Looks more reasonable.
>

Indeed! I will invert the order.

(I wonder if the regulator disabling order actually makes a difference
though).

> > +
> > +	return;
> > +
> > +error_vcc_disable:
> > +	dev_err(thc63->dev, "Failed to disable regulator %u\n", i);
> > +}
> > +
> > +struct drm_bridge_funcs thc63_bridge_func = {
> > +	.attach	= thc63_attach,
> > +	.enable = thc63_enable,
> > +	.disable = thc63_disable,
> > +};
> > +
> > +static int thc63_parse_dt(struct thc63_dev *thc63)
> > +{
> > +	struct device_node *thc63_out;
> > +	struct device_node *remote;
> > +	int ret = 0;
> > +
> > +	thc63_out = of_graph_get_endpoint_by_regs(thc63->dev->of_node, 2, -1);
>
> Please define and use enums for port number, it will be more clear.
>

yup

> > +	if (!thc63_out) {
> > +		dev_err(thc63->dev, "Missing endpoint in Port@2\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	remote = of_graph_get_remote_port_parent(thc63_out);
> > +	if (!remote) {
> > +		dev_err(thc63->dev, "Endpoint in Port@2 unconnected\n");
> > +		ret = -ENODEV;
> > +		goto error_put_out_node;
> > +	}
> > +
> > +	if (!of_device_is_available(remote)) {
> > +		dev_err(thc63->dev, "Port@2 remote endpoint is disabled\n");
> > +		ret = -ENODEV;
> > +		goto error_put_remote_node;
> > +	}
> > +
> > +	thc63->next = of_drm_find_bridge(remote);
> > +	if (!thc63->next)
> > +		ret = -EPROBE_DEFER;
> > +
> > +error_put_remote_node:
> > +	of_node_put(remote);
> > +error_put_out_node:
> > +	of_node_put(thc63_out);
> > +
> > +	return ret;
> > +}
> > +
> > +static int thc63_gpio_init(struct thc63_dev *thc63)
> > +{
> > +	thc63->pwdn = devm_gpiod_get_optional(thc63->dev, "pwdn",
> > +					      GPIOD_OUT_LOW);
> Shouldn't be GPIOD_OUT_HIGH - bridge initially disabled?

No, the PWDN gpio is active low, it puts the chip in power down mode
when the physical line level is set to 0.

That's another confusing thing, when requesting the GPIO, the actual
physical line value has to be provided, while when "set_value()" the
logical one is requested, iirc.

Being the GPIO defined as active low, in power enable we set it to
"logical inactive" == "physical 1", while during power disable it has
to be set to "logical active" == "physical 0"

Not the right place to complain here, but imo that's not consistent.
Or have I misinterpreted the APIs? I cannot do much test, as in my setup
the PWDN pin is hardwired to +vcc (through a physical switch, not
controlled through a GPIO though).

Thanks
   j

>
> Regards
> Andrzej
> > +	if (IS_ERR(thc63->pwdn)) {
> > +		dev_err(thc63->dev, "Unable to get GPIO \"pwdn\"\n");
> > +		return PTR_ERR(thc63->pwdn);
> > +	}
> > +
> > +	thc63->oe = devm_gpiod_get_optional(thc63->dev, "oe", GPIOD_OUT_LOW);
> > +	if (IS_ERR(thc63->oe)) {
> > +		dev_err(thc63->dev, "Unable to get GPIO \"oe\"\n");
> > +		return PTR_ERR(thc63->oe);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int thc63_regulator_init(struct thc63_dev *thc63)
> > +{
> > +	struct regulator **reg;
> > +	int i;
> > +
> > +	reg = &thc63->vccs[0];
> > +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++, reg++) {
> > +		*reg = devm_regulator_get_optional(thc63->dev,
> > +						   thc63_reg_names[i]);
> > +		if (IS_ERR(*reg)) {
> > +			if (PTR_ERR(*reg) == -EPROBE_DEFER)
> > +				return -EPROBE_DEFER;
> > +			*reg = NULL;
> > +		}
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int thc63_probe(struct platform_device *pdev)
> > +{
> > +	struct thc63_dev *thc63;
> > +	int ret;
> > +
> > +	thc63 = devm_kzalloc(&pdev->dev, sizeof(*thc63), GFP_KERNEL);
> > +	if (!thc63)
> > +		return -ENOMEM;
> > +
> > +	thc63->dev = &pdev->dev;
> > +	platform_set_drvdata(pdev, thc63);
> > +
> > +	ret = thc63_regulator_init(thc63);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = thc63_gpio_init(thc63);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = thc63_parse_dt(thc63);
> > +	if (ret)
> > +		return ret;
> > +
> > +	thc63->bridge.driver_private = thc63;
> > +	thc63->bridge.of_node = pdev->dev.of_node;
> > +	thc63->bridge.funcs = &thc63_bridge_func;
> > +
> > +	drm_bridge_add(&thc63->bridge);
> > +
> > +	return 0;
> > +}
> > +
> > +static int thc63_remove(struct platform_device *pdev)
> > +{
> > +	struct thc63_dev *thc63 = platform_get_drvdata(pdev);
> > +
> > +	drm_bridge_remove(&thc63->bridge);
> > +
> > +	return 0;
> > +}
> > +
> > +#ifdef CONFIG_OF
> > +static const struct of_device_id thc63_match[] = {
> > +	{ .compatible = "thine,thc63lvd1024", },
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, thc63_match);
> > +#endif
> > +
> > +static struct platform_driver thc63_driver = {
> > +	.probe	= thc63_probe,
> > +	.remove	= thc63_remove,
> > +	.driver	= {
> > +		.name		= "thc63lvd1024",
> > +		.of_match_table	= thc63_match,
> > +	},
> > +};
> > +module_platform_driver(thc63_driver);
> > +
> > +MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
> > +MODULE_DESCRIPTION("Thine THC63LVD1024 LVDS decoder DRM bridge driver");
> > +MODULE_LICENSE("GPL v2");
>
>
Sergei Shtylyov March 14, 2018, 5:09 p.m. UTC | #4 
On 03/13/2018 05:30 PM, Jacopo Mondi wrote:

> Add DRM bridge driver for Thine THC63LVD1024 LVDS to digital parallel
> output decoder.
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
[...]
> diff --git a/drivers/gpu/drm/bridge/thc63lvd1024.c b/drivers/gpu/drm/bridge/thc63lvd1024.c
> new file mode 100644
> index 0000000..4b059c0
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/thc63lvd1024.c
> @@ -0,0 +1,241 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * THC63LVD1024 LVDS to parallel data DRM bridge driver.
> + *
> + * Copyright (C) 2018 Jacopo Mondi <jacopo+renesas@jmondi.org>
> + */
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_panel.h>
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/of_graph.h>
> +#include <linux/regulator/consumer.h>
> +
> +static const char * const thc63_reg_names[] = {
> +	"vcc", "lvcc", "pvcc", "cvcc", };

   Your bracing style is pretty strange -- neither here nor there. Please place };
on the next line...

[...]
> +static void thc63_enable(struct drm_bridge *bridge)
> +{
> +	struct thc63_dev *thc63 = to_thc63(bridge);
> +	struct regulator *vcc;
> +	unsigned int i;
> +	int ret;
> +
> +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
> +		vcc = thc63->vccs[i];
> +		if (vcc) {
> +			ret = regulator_enable(vcc);
> +			if (ret)

   You hardly need this variable, could do a call right in this *if*.

[...]
> +error_vcc_enable:
> +	dev_err(thc63->dev, "Failed to enable regulator %u\n", i);
> +}
> +

   Why not do this instead of *goto* before?
 
> +static void thc63_disable(struct drm_bridge *bridge)
> +{
> +	struct thc63_dev *thc63 = to_thc63(bridge);
> +	struct regulator *vcc;
> +	unsigned int i;
> +	int ret;
> +
> +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
> +		vcc = thc63->vccs[i];
> +		if (vcc) {
> +			ret = regulator_disable(vcc);
> +			if (ret)

   Again, no need for 'ret' whatsoever...

> +				goto error_vcc_disable;
> +		}
> +	}
> +
> +	if (thc63->pwdn)
> +		gpiod_set_value(thc63->pwdn, 1);
> +
> +	if (thc63->oe)
> +		gpiod_set_value(thc63->oe, 0);
> +
> +	return;
> +
> +error_vcc_disable:
> +	dev_err(thc63->dev, "Failed to disable regulator %u\n", i);

   Again, why not do it instead of *goto*?

[...]
> +static int thc63_gpio_init(struct thc63_dev *thc63)
> +{
> +	thc63->pwdn = devm_gpiod_get_optional(thc63->dev, "pwdn",
> +					      GPIOD_OUT_LOW);
> +	if (IS_ERR(thc63->pwdn)) {
> +		dev_err(thc63->dev, "Unable to get GPIO \"pwdn\"\n");

   "pwdn-gpios" maybe?

> +		return PTR_ERR(thc63->pwdn);
> +	}
> +
> +	thc63->oe = devm_gpiod_get_optional(thc63->dev, "oe", GPIOD_OUT_LOW);
> +	if (IS_ERR(thc63->oe)) {
> +		dev_err(thc63->dev, "Unable to get GPIO \"oe\"\n");

   "oe-gpios" maybe?

[...]

MBR, Sergei
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Jacopo Mondi March 14, 2018, 6:04 p.m. UTC | #5 
Hi Sergei,
   thanks for review

On Wed, Mar 14, 2018 at 08:09:52PM +0300, Sergei Shtylyov wrote:
> On 03/13/2018 05:30 PM, Jacopo Mondi wrote:
>
> > Add DRM bridge driver for Thine THC63LVD1024 LVDS to digital parallel
> > output decoder.
> >
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> [...]
> > diff --git a/drivers/gpu/drm/bridge/thc63lvd1024.c b/drivers/gpu/drm/bridge/thc63lvd1024.c
> > new file mode 100644
> > index 0000000..4b059c0
> > --- /dev/null
> > +++ b/drivers/gpu/drm/bridge/thc63lvd1024.c
> > @@ -0,0 +1,241 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * THC63LVD1024 LVDS to parallel data DRM bridge driver.
> > + *
> > + * Copyright (C) 2018 Jacopo Mondi <jacopo+renesas@jmondi.org>
> > + */
> > +
> > +#include <drm/drmP.h>
> > +#include <drm/drm_bridge.h>
> > +#include <drm/drm_panel.h>
> > +
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/of_graph.h>
> > +#include <linux/regulator/consumer.h>
> > +
> > +static const char * const thc63_reg_names[] = {
> > +	"vcc", "lvcc", "pvcc", "cvcc", };
>
>    Your bracing style is pretty strange -- neither here nor there. Please place };
> on the next line...

Yeah, I had doubt about this.. The most common style I found around is

static const char * const foo[] = {
        "bar",
        "baz",
        "...",
};

But seems really too many lines for a bunch of 4 character strings...

>
> [...]
> > +static void thc63_enable(struct drm_bridge *bridge)
> > +{
> > +	struct thc63_dev *thc63 = to_thc63(bridge);
> > +	struct regulator *vcc;
> > +	unsigned int i;
> > +	int ret;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
> > +		vcc = thc63->vccs[i];
> > +		if (vcc) {
> > +			ret = regulator_enable(vcc);
> > +			if (ret)
>
>    You hardly need this variable, could do a call right in this *if*.
>
> [...]
> > +error_vcc_enable:
> > +	dev_err(thc63->dev, "Failed to enable regulator %u\n", i);
> > +}
> > +
>
>    Why not do this instead of *goto* before?

Well, goto breaks the loop, if I only print out the error message, the
enable sequence will go on and enable the other regulators.

I can print out and break, but I don't see that much benefit

One thing I could do instead, is not only print out the error message,
but disable the already enabled regulators if one fails to start.

>
> > +static void thc63_disable(struct drm_bridge *bridge)
> > +{
> > +	struct thc63_dev *thc63 = to_thc63(bridge);
> > +	struct regulator *vcc;
> > +	unsigned int i;
> > +	int ret;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
> > +		vcc = thc63->vccs[i];
> > +		if (vcc) {
> > +			ret = regulator_disable(vcc);
> > +			if (ret)
>
>    Again, no need for 'ret' whatsoever...
>
> > +				goto error_vcc_disable;
> > +		}
> > +	}
> > +
> > +	if (thc63->pwdn)
> > +		gpiod_set_value(thc63->pwdn, 1);
> > +
> > +	if (thc63->oe)
> > +		gpiod_set_value(thc63->oe, 0);
> > +
> > +	return;
> > +
> > +error_vcc_disable:
> > +	dev_err(thc63->dev, "Failed to disable regulator %u\n", i);
>
>    Again, why not do it instead of *goto*?

ditto

>
> [...]
> > +static int thc63_gpio_init(struct thc63_dev *thc63)
> > +{
> > +	thc63->pwdn = devm_gpiod_get_optional(thc63->dev, "pwdn",
> > +					      GPIOD_OUT_LOW);
> > +	if (IS_ERR(thc63->pwdn)) {
> > +		dev_err(thc63->dev, "Unable to get GPIO \"pwdn\"\n");
>
>    "pwdn-gpios" maybe?
>
> > +		return PTR_ERR(thc63->pwdn);
> > +	}
> > +
> > +	thc63->oe = devm_gpiod_get_optional(thc63->dev, "oe", GPIOD_OUT_LOW);
> > +	if (IS_ERR(thc63->oe)) {
> > +		dev_err(thc63->dev, "Unable to get GPIO \"oe\"\n");
>
>    "oe-gpios" maybe?

Are you referring to the error message? I can change this, but again, I
see no standards around.

Thanks
   j

>
> [...]
>
> MBR, Sergei
Sergei Shtylyov March 14, 2018, 6:17 p.m. UTC | #6 
On 03/14/2018 09:04 PM, jacopo mondi wrote:

>>> Add DRM bridge driver for Thine THC63LVD1024 LVDS to digital parallel
>>> output decoder.
>>>
>>> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
>> [...]
>>> diff --git a/drivers/gpu/drm/bridge/thc63lvd1024.c b/drivers/gpu/drm/bridge/thc63lvd1024.c
>>> new file mode 100644
>>> index 0000000..4b059c0
>>> --- /dev/null
>>> +++ b/drivers/gpu/drm/bridge/thc63lvd1024.c
>>> @@ -0,0 +1,241 @@
[...]
>>> +static void thc63_enable(struct drm_bridge *bridge)
>>> +{
>>> +	struct thc63_dev *thc63 = to_thc63(bridge);
>>> +	struct regulator *vcc;
>>> +	unsigned int i;
>>> +	int ret;
>>> +
>>> +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
>>> +		vcc = thc63->vccs[i];
>>> +		if (vcc) {
>>> +			ret = regulator_enable(vcc);
>>> +			if (ret)
>>
>>    You hardly need this variable, could do a call right in this *if*.
>>
>> [...]
>>> +error_vcc_enable:
>>> +	dev_err(thc63->dev, "Failed to enable regulator %u\n", i);
>>> +}
>>> +
>>
>>    Why not do this instead of *goto* before?
> 
> Well, goto breaks the loop, if I only print out the error message, the
> enable sequence will go on and enable the other regulators.

> I can print out and break, but I don't see that much benefit

   Sorry, I meant that you should *return* there instead of *goto*.

> One thing I could do instead, is not only print out the error message,
> but disable the already enabled regulators if one fails to start.

   Yeah, probably...

[...]
>>> +static int thc63_gpio_init(struct thc63_dev *thc63)
>>> +{
>>> +	thc63->pwdn = devm_gpiod_get_optional(thc63->dev, "pwdn",
>>> +					      GPIOD_OUT_LOW);
>>> +	if (IS_ERR(thc63->pwdn)) {
>>> +		dev_err(thc63->dev, "Unable to get GPIO \"pwdn\"\n");
>>
>>    "pwdn-gpios" maybe?
>>
>>> +		return PTR_ERR(thc63->pwdn);
>>> +	}
>>> +
>>> +	thc63->oe = devm_gpiod_get_optional(thc63->dev, "oe", GPIOD_OUT_LOW);
>>> +	if (IS_ERR(thc63->oe)) {
>>> +		dev_err(thc63->dev, "Unable to get GPIO \"oe\"\n");
>>
>>    "oe-gpios" maybe?
> 
> Are you referring to the error message?

   Yes, seems more clear what to look for this way, IMHO...

[...]

MBR, Sergei

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Andrzej Hajda March 15, 2018, 9:44 a.m. UTC | #7 
On 14.03.2018 11:09, jacopo mondi wrote:
> Hi Andrzej,
>     thanks for review
>
> On Wed, Mar 14, 2018 at 09:42:36AM +0100, Andrzej Hajda wrote:
>> On 13.03.2018 15:30, Jacopo Mondi wrote:
>>> Add DRM bridge driver for Thine THC63LVD1024 LVDS to digital parallel
>>> output decoder.
>> IMO converter suits here better, but it is just suggestion.
>>
>>> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
>>> ---
>>>  drivers/gpu/drm/bridge/Kconfig        |   7 +
>>>  drivers/gpu/drm/bridge/Makefile       |   1 +
>>>  drivers/gpu/drm/bridge/thc63lvd1024.c | 241 ++++++++++++++++++++++++++++++++++
>>>  3 files changed, 249 insertions(+)
>>>  create mode 100644 drivers/gpu/drm/bridge/thc63lvd1024.c
>>>
>>> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
>>> index 3b99d5a..facf6bd 100644
>>> --- a/drivers/gpu/drm/bridge/Kconfig
>>> +++ b/drivers/gpu/drm/bridge/Kconfig
>>> @@ -92,6 +92,13 @@ config DRM_SII9234
>>>  	  It is an I2C driver, that detects connection of MHL bridge
>>>  	  and starts encapsulation of HDMI signal.
>>>
>>> +config DRM_THINE_THC63LVD1024
>>> +	tristate "Thine THC63LVD1024 LVDS decoder bridge"
>>> +	depends on OF
>>> +	select DRM_PANEL_BRIDGE
>> You don't use PANEL_BRIDGE, it should be possible to drop the select.
>>
> Ack
>
>>> +	---help---
>>> +	  Thine THC63LVD1024 LVDS decoder bridge driver.
>> Decoder to what?
>> Maybe it would be better to say it is LVDS/parallel or LVDS/RGB
>> converter or bridge.
> "LVDS to digital CMOS/TTL parallel data converter" as the manual
> describes the chip?

Should work, unless we want some consistency in interface names, we have
already: parallel / DPI / RGB. I am little bit confused about relations
between them so I do not want to enforce any.


>
>>> +
>>>  config DRM_TOSHIBA_TC358767
>>>  	tristate "Toshiba TC358767 eDP bridge"
>>>  	depends on OF
>>> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
>>> index 373eb28..fd90b16 100644
>>> --- a/drivers/gpu/drm/bridge/Makefile
>>> +++ b/drivers/gpu/drm/bridge/Makefile
>>> @@ -8,6 +8,7 @@ obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
>>>  obj-$(CONFIG_DRM_SIL_SII8620) += sil-sii8620.o
>>>  obj-$(CONFIG_DRM_SII902X) += sii902x.o
>>>  obj-$(CONFIG_DRM_SII9234) += sii9234.o
>>> +obj-$(CONFIG_DRM_THINE_THC63LVD1024) += thc63lvd1024.o
>>>  obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
>>>  obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix/
>>>  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
>>> diff --git a/drivers/gpu/drm/bridge/thc63lvd1024.c b/drivers/gpu/drm/bridge/thc63lvd1024.c
>>> new file mode 100644
>>> index 0000000..4b059c0
>>> --- /dev/null
>>> +++ b/drivers/gpu/drm/bridge/thc63lvd1024.c
>>> @@ -0,0 +1,241 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * THC63LVD1024 LVDS to parallel data DRM bridge driver.
>>> + *
>>> + * Copyright (C) 2018 Jacopo Mondi <jacopo+renesas@jmondi.org>
>>> + */
>>> +
>>> +#include <drm/drmP.h>
>>> +#include <drm/drm_bridge.h>
>>> +#include <drm/drm_panel.h>
>>> +
>>> +#include <linux/gpio/consumer.h>
>>> +#include <linux/of_graph.h>
>>> +#include <linux/regulator/consumer.h>
>>> +
>>> +static const char * const thc63_reg_names[] = {
>>> +	"vcc", "lvcc", "pvcc", "cvcc", };
>>> +
>>> +struct thc63_dev {
>>> +	struct device *dev;
>>> +
>>> +	struct regulator *vccs[ARRAY_SIZE(thc63_reg_names)];
>>> +
>>> +	struct gpio_desc *pwdn;
>>> +	struct gpio_desc *oe;
>>> +
>>> +	struct drm_bridge bridge;
>>> +	struct drm_bridge *next;
>>> +};
>>> +
>>> +static inline struct thc63_dev *to_thc63(struct drm_bridge *bridge)
>>> +{
>>> +	return container_of(bridge, struct thc63_dev, bridge);
>>> +}
>>> +
>>> +static int thc63_attach(struct drm_bridge *bridge)
>>> +{
>>> +	struct thc63_dev *thc63 = to_thc63(bridge);
>>> +
>>> +	return drm_bridge_attach(bridge->encoder, thc63->next, bridge);
>>> +}
>>> +
>>> +static void thc63_enable(struct drm_bridge *bridge)
>>> +{
>>> +	struct thc63_dev *thc63 = to_thc63(bridge);
>>> +	struct regulator *vcc;
>>> +	unsigned int i;
>>> +	int ret;
>>> +
>>> +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
>>> +		vcc = thc63->vccs[i];
>>> +		if (vcc) {
>>> +			ret = regulator_enable(vcc);
>>> +			if (ret)
>>> +				goto error_vcc_enable;
>>> +		}
>>> +	}
>>> +
>>> +	if (thc63->pwdn)
>>> +		gpiod_set_value(thc63->pwdn, 0);
>>> +
>>> +	if (thc63->oe)
>>> +		gpiod_set_value(thc63->oe, 1);
>>> +
>>> +	return;
>>> +
>>> +error_vcc_enable:
>>> +	dev_err(thc63->dev, "Failed to enable regulator %u\n", i);
>>> +}
>>> +
>>> +static void thc63_disable(struct drm_bridge *bridge)
>>> +{
>>> +	struct thc63_dev *thc63 = to_thc63(bridge);
>>> +	struct regulator *vcc;
>>> +	unsigned int i;
>>> +	int ret;
>>> +
>>> +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++) {
>>> +		vcc = thc63->vccs[i];
>>> +		if (vcc) {
>>> +			ret = regulator_disable(vcc);
>>> +			if (ret)
>>> +				goto error_vcc_disable;
>> I think in disable path you can report an error and continue - should be
>> safer.
>>
> Ack
>
>>> +		}
>>> +	}
>>> +
>>> +	if (thc63->pwdn)
>>> +		gpiod_set_value(thc63->pwdn, 1);
>>> +
>>> +	if (thc63->oe)
>>> +		gpiod_set_value(thc63->oe, 0);
>> Usually disable uses reverse order. Ie first disable oe, then, pwdn,
>> then regulators, also in reverse order.
>> Looks more reasonable.
>>
> Indeed! I will invert the order.
>
> (I wonder if the regulator disabling order actually makes a difference
> though).
>>> +
>>> +	return;
>>> +
>>> +error_vcc_disable:
>>> +	dev_err(thc63->dev, "Failed to disable regulator %u\n", i);
>>> +}
>>> +
>>> +struct drm_bridge_funcs thc63_bridge_func = {
>>> +	.attach	= thc63_attach,
>>> +	.enable = thc63_enable,
>>> +	.disable = thc63_disable,
>>> +};
>>> +
>>> +static int thc63_parse_dt(struct thc63_dev *thc63)
>>> +{
>>> +	struct device_node *thc63_out;
>>> +	struct device_node *remote;
>>> +	int ret = 0;
>>> +
>>> +	thc63_out = of_graph_get_endpoint_by_regs(thc63->dev->of_node, 2, -1);
>> Please define and use enums for port number, it will be more clear.
>>
> yup
>
>>> +	if (!thc63_out) {
>>> +		dev_err(thc63->dev, "Missing endpoint in Port@2\n");
>>> +		return -ENODEV;
>>> +	}
>>> +
>>> +	remote = of_graph_get_remote_port_parent(thc63_out);
>>> +	if (!remote) {
>>> +		dev_err(thc63->dev, "Endpoint in Port@2 unconnected\n");
>>> +		ret = -ENODEV;
>>> +		goto error_put_out_node;
>>> +	}
>>> +
>>> +	if (!of_device_is_available(remote)) {
>>> +		dev_err(thc63->dev, "Port@2 remote endpoint is disabled\n");
>>> +		ret = -ENODEV;
>>> +		goto error_put_remote_node;
>>> +	}
>>> +
>>> +	thc63->next = of_drm_find_bridge(remote);
>>> +	if (!thc63->next)
>>> +		ret = -EPROBE_DEFER;
>>> +
>>> +error_put_remote_node:
>>> +	of_node_put(remote);
>>> +error_put_out_node:
>>> +	of_node_put(thc63_out);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int thc63_gpio_init(struct thc63_dev *thc63)
>>> +{
>>> +	thc63->pwdn = devm_gpiod_get_optional(thc63->dev, "pwdn",
>>> +					      GPIOD_OUT_LOW);
>> Shouldn't be GPIOD_OUT_HIGH - bridge initially disabled?
> No, the PWDN gpio is active low, it puts the chip in power down mode
> when the physical line level is set to 0.
>
> That's another confusing thing, when requesting the GPIO, the actual
> physical line value has to be provided, while when "set_value()" the
> logical one is requested, iirc.

I think it is opposite, only *raw* functions uses physical level. Other
uses logical level.

>
> Being the GPIO defined as active low, in power enable we set it to
> "logical inactive" == "physical 1", while during power disable it has
> to be set to "logical active" == "physical 0"
>
> Not the right place to complain here, but imo that's not consistent.
> Or have I misinterpreted the APIs? I cannot do much test, as in my setup
> the PWDN pin is hardwired to +vcc (through a physical switch, not
> controlled through a GPIO though).

devm_gpiod_get_optional calls (indirectly) gpiod_configure_flags, which
calls gpiod_direction_output which uses logical levels.

Regards
Andrzej

>
> Thanks
>    j
>
>> Regards
>> Andrzej
>>> +	if (IS_ERR(thc63->pwdn)) {
>>> +		dev_err(thc63->dev, "Unable to get GPIO \"pwdn\"\n");
>>> +		return PTR_ERR(thc63->pwdn);
>>> +	}
>>> +
>>> +	thc63->oe = devm_gpiod_get_optional(thc63->dev, "oe", GPIOD_OUT_LOW);
>>> +	if (IS_ERR(thc63->oe)) {
>>> +		dev_err(thc63->dev, "Unable to get GPIO \"oe\"\n");
>>> +		return PTR_ERR(thc63->oe);
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int thc63_regulator_init(struct thc63_dev *thc63)
>>> +{
>>> +	struct regulator **reg;
>>> +	int i;
>>> +
>>> +	reg = &thc63->vccs[0];
>>> +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++, reg++) {
>>> +		*reg = devm_regulator_get_optional(thc63->dev,
>>> +						   thc63_reg_names[i]);
>>> +		if (IS_ERR(*reg)) {
>>> +			if (PTR_ERR(*reg) == -EPROBE_DEFER)
>>> +				return -EPROBE_DEFER;
>>> +			*reg = NULL;
>>> +		}
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int thc63_probe(struct platform_device *pdev)
>>> +{
>>> +	struct thc63_dev *thc63;
>>> +	int ret;
>>> +
>>> +	thc63 = devm_kzalloc(&pdev->dev, sizeof(*thc63), GFP_KERNEL);
>>> +	if (!thc63)
>>> +		return -ENOMEM;
>>> +
>>> +	thc63->dev = &pdev->dev;
>>> +	platform_set_drvdata(pdev, thc63);
>>> +
>>> +	ret = thc63_regulator_init(thc63);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	ret = thc63_gpio_init(thc63);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	ret = thc63_parse_dt(thc63);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	thc63->bridge.driver_private = thc63;
>>> +	thc63->bridge.of_node = pdev->dev.of_node;
>>> +	thc63->bridge.funcs = &thc63_bridge_func;
>>> +
>>> +	drm_bridge_add(&thc63->bridge);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int thc63_remove(struct platform_device *pdev)
>>> +{
>>> +	struct thc63_dev *thc63 = platform_get_drvdata(pdev);
>>> +
>>> +	drm_bridge_remove(&thc63->bridge);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +#ifdef CONFIG_OF
>>> +static const struct of_device_id thc63_match[] = {
>>> +	{ .compatible = "thine,thc63lvd1024", },
>>> +	{ },
>>> +};
>>> +MODULE_DEVICE_TABLE(of, thc63_match);
>>> +#endif
>>> +
>>> +static struct platform_driver thc63_driver = {
>>> +	.probe	= thc63_probe,
>>> +	.remove	= thc63_remove,
>>> +	.driver	= {
>>> +		.name		= "thc63lvd1024",
>>> +		.of_match_table	= thc63_match,
>>> +	},
>>> +};
>>> +module_platform_driver(thc63_driver);
>>> +
>>> +MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
>>> +MODULE_DESCRIPTION("Thine THC63LVD1024 LVDS decoder DRM bridge driver");
>>> +MODULE_LICENSE("GPL v2");
>>

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Jacopo Mondi March 15, 2018, 10:30 a.m. UTC | #8 
HI Andrezej,

On Thu, Mar 15, 2018 at 10:44:42AM +0100, Andrzej Hajda wrote:
> On 14.03.2018 11:09, jacopo mondi wrote:
> > Hi Andrzej,
> >     thanks for review
> >
> > On Wed, Mar 14, 2018 at 09:42:36AM +0100, Andrzej Hajda wrote:
> >> On 13.03.2018 15:30, Jacopo Mondi wrote:
> >>> Add DRM bridge driver for Thine THC63LVD1024 LVDS to digital parallel
> >>> output decoder.
> >> IMO converter suits here better, but it is just suggestion.
> >>
> >>> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> >>> ---
> >>>  drivers/gpu/drm/bridge/Kconfig        |   7 +
> >>>  drivers/gpu/drm/bridge/Makefile       |   1 +
> >>>  drivers/gpu/drm/bridge/thc63lvd1024.c | 241 ++++++++++++++++++++++++++++++++++
> >>>  3 files changed, 249 insertions(+)
> >>>  create mode 100644 drivers/gpu/drm/bridge/thc63lvd1024.c
> >>>
> >>> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> >>> index 3b99d5a..facf6bd 100644
> >>> --- a/drivers/gpu/drm/bridge/Kconfig
> >>> +++ b/drivers/gpu/drm/bridge/Kconfig
> >>> @@ -92,6 +92,13 @@ config DRM_SII9234
> >>>  	  It is an I2C driver, that detects connection of MHL bridge
> >>>  	  and starts encapsulation of HDMI signal.
> >>>
> >>> +config DRM_THINE_THC63LVD1024
> >>> +	tristate "Thine THC63LVD1024 LVDS decoder bridge"
> >>> +	depends on OF
> >>> +	select DRM_PANEL_BRIDGE
> >> You don't use PANEL_BRIDGE, it should be possible to drop the select.
> >>
> > Ack
> >
> >>> +	---help---
> >>> +	  Thine THC63LVD1024 LVDS decoder bridge driver.
> >> Decoder to what?
> >> Maybe it would be better to say it is LVDS/parallel or LVDS/RGB
> >> converter or bridge.
> > "LVDS to digital CMOS/TTL parallel data converter" as the manual
> > describes the chip?
>
> Should work, unless we want some consistency in interface names, we have
> already: parallel / DPI / RGB. I am little bit confused about relations
> between them so I do not want to enforce any.

config DRM_THINE_THC63LVD1024
	tristate "Thine THC63LVD1024 LVDS decoder bridge"
	depends on OF
	---help---
	  Thine THC63LVD1024 LVDS/parallel converter driver.

I guess this is consistent with other symbol descriptions I found

>

[snip]
>
> >>> +
> >>> +static int thc63_gpio_init(struct thc63_dev *thc63)
> >>> +{
> >>> +	thc63->pwdn = devm_gpiod_get_optional(thc63->dev, "pwdn",
> >>> +					      GPIOD_OUT_LOW);
> >> Shouldn't be GPIOD_OUT_HIGH - bridge initially disabled?
> > No, the PWDN gpio is active low, it puts the chip in power down mode
> > when the physical line level is set to 0.
> >
> > That's another confusing thing, when requesting the GPIO, the actual
> > physical line value has to be provided, while when "set_value()" the
> > logical one is requested, iirc.
>
> I think it is opposite, only *raw* functions uses physical level. Other
> uses logical level.
>
> >
> > Being the GPIO defined as active low, in power enable we set it to
> > "logical inactive" == "physical 1", while during power disable it has
> > to be set to "logical active" == "physical 0"
> >
> > Not the right place to complain here, but imo that's not consistent.
> > Or have I misinterpreted the APIs? I cannot do much test, as in my setup
> > the PWDN pin is hardwired to +vcc (through a physical switch, not
> > controlled through a GPIO though).
>
> devm_gpiod_get_optional calls (indirectly) gpiod_configure_flags, which
> calls gpiod_direction_output which uses logical levels.

I clearly mis-interpreted the APIs.

I'll fix and I'm sending v4 out shortly.

Thanks
   j

>
> Regards
> Andrzej
>
> >
> > Thanks
> >    j
> >
> >> Regards
> >> Andrzej
> >>> +	if (IS_ERR(thc63->pwdn)) {
> >>> +		dev_err(thc63->dev, "Unable to get GPIO \"pwdn\"\n");
> >>> +		return PTR_ERR(thc63->pwdn);
> >>> +	}
> >>> +
> >>> +	thc63->oe = devm_gpiod_get_optional(thc63->dev, "oe", GPIOD_OUT_LOW);
> >>> +	if (IS_ERR(thc63->oe)) {
> >>> +		dev_err(thc63->dev, "Unable to get GPIO \"oe\"\n");
> >>> +		return PTR_ERR(thc63->oe);
> >>> +	}
> >>> +
> >>> +	return 0;
> >>> +}
> >>> +
> >>> +static int thc63_regulator_init(struct thc63_dev *thc63)
> >>> +{
> >>> +	struct regulator **reg;
> >>> +	int i;
> >>> +
> >>> +	reg = &thc63->vccs[0];
> >>> +	for (i = 0; i < ARRAY_SIZE(thc63->vccs); i++, reg++) {
> >>> +		*reg = devm_regulator_get_optional(thc63->dev,
> >>> +						   thc63_reg_names[i]);
> >>> +		if (IS_ERR(*reg)) {
> >>> +			if (PTR_ERR(*reg) == -EPROBE_DEFER)
> >>> +				return -EPROBE_DEFER;
> >>> +			*reg = NULL;
> >>> +		}
> >>> +	}
> >>> +
> >>> +	return 0;
> >>> +}
> >>> +
> >>> +static int thc63_probe(struct platform_device *pdev)
> >>> +{
> >>> +	struct thc63_dev *thc63;
> >>> +	int ret;
> >>> +
> >>> +	thc63 = devm_kzalloc(&pdev->dev, sizeof(*thc63), GFP_KERNEL);
> >>> +	if (!thc63)
> >>> +		return -ENOMEM;
> >>> +
> >>> +	thc63->dev = &pdev->dev;
> >>> +	platform_set_drvdata(pdev, thc63);
> >>> +
> >>> +	ret = thc63_regulator_init(thc63);
> >>> +	if (ret)
> >>> +		return ret;
> >>> +
> >>> +	ret = thc63_gpio_init(thc63);
> >>> +	if (ret)
> >>> +		return ret;
> >>> +
> >>> +	ret = thc63_parse_dt(thc63);
> >>> +	if (ret)
> >>> +		return ret;
> >>> +
> >>> +	thc63->bridge.driver_private = thc63;
> >>> +	thc63->bridge.of_node = pdev->dev.of_node;
> >>> +	thc63->bridge.funcs = &thc63_bridge_func;
> >>> +
> >>> +	drm_bridge_add(&thc63->bridge);
> >>> +
> >>> +	return 0;
> >>> +}
> >>> +
> >>> +static int thc63_remove(struct platform_device *pdev)
> >>> +{
> >>> +	struct thc63_dev *thc63 = platform_get_drvdata(pdev);
> >>> +
> >>> +	drm_bridge_remove(&thc63->bridge);
> >>> +
> >>> +	return 0;
> >>> +}
> >>> +
> >>> +#ifdef CONFIG_OF
> >>> +static const struct of_device_id thc63_match[] = {
> >>> +	{ .compatible = "thine,thc63lvd1024", },
> >>> +	{ },
> >>> +};
> >>> +MODULE_DEVICE_TABLE(of, thc63_match);
> >>> +#endif
> >>> +
> >>> +static struct platform_driver thc63_driver = {
> >>> +	.probe	= thc63_probe,
> >>> +	.remove	= thc63_remove,
> >>> +	.driver	= {
> >>> +		.name		= "thc63lvd1024",
> >>> +		.of_match_table	= thc63_match,
> >>> +	},
> >>> +};
> >>> +module_platform_driver(thc63_driver);
> >>> +
> >>> +MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
> >>> +MODULE_DESCRIPTION("Thine THC63LVD1024 LVDS decoder DRM bridge driver");
> >>> +MODULE_LICENSE("GPL v2");
> >>
>