[v2] mdio_bus: Issue GPIO RESET to PHYs.

Message ID daa29a99-0a17-d316-57eb-3e6162938d8d@ti.com
State Changes Requested
Delegated to: David Miller
Headers show

Commit Message

Roger Quadros April 20, 2017, 8:39 a.m.
Some boards [1] leave the PHYs at an invalid state
during system power-up or reset thus causing unreliability
issues with the PHY which manifests as PHY not being detected
or link not functional. To fix this, these PHYs need to be RESET
via a GPIO connected to the PHY's RESET pin.

Some boards have a single GPIO controlling the PHY RESET pin of all
PHYs on the bus whereas some others have separate GPIOs controlling
individual PHY RESETs.

In both cases, the RESET de-assertion cannot be done in the PHY driver
as the PHY will not probe till its reset is de-asserted.
So do the RESET de-assertion in the MDIO bus driver.

[1] - am572x-idk, am571x-idk, a437x-idk

Signed-off-by: Roger Quadros <rogerq@ti.com>
---
v2:
- add device tree binding document (mdio.txt)
- specify default reset delay in of_mdio.c instead of mdio_bus.c

 Documentation/devicetree/bindings/net/mdio.txt | 20 ++++++++++++++++++++
 drivers/net/phy/mdio_bus.c                     | 22 ++++++++++++++++++++++
 drivers/of/of_mdio.c                           |  7 +++++++
 include/linux/phy.h                            |  5 +++++
 4 files changed, 54 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/mdio.txt

Comments

Andrew Lunn April 20, 2017, 1:13 p.m. | #1
On Thu, Apr 20, 2017 at 11:39:20AM +0300, Roger Quadros wrote:
> Some boards [1] leave the PHYs at an invalid state
> during system power-up or reset thus causing unreliability
> issues with the PHY which manifests as PHY not being detected
> or link not functional. To fix this, these PHYs need to be RESET
> via a GPIO connected to the PHY's RESET pin.
> 
> Some boards have a single GPIO controlling the PHY RESET pin of all
> PHYs on the bus whereas some others have separate GPIOs controlling
> individual PHY RESETs.
> 
> In both cases, the RESET de-assertion cannot be done in the PHY driver
> as the PHY will not probe till its reset is de-asserted.
> So do the RESET de-assertion in the MDIO bus driver.

Hi Roger

Networking patches should include in the subject line which tree they
are for. In this case, net-next. So please make the Subject

[patch v3 net-next] .....

> [1] - am572x-idk, am571x-idk, a437x-idk
> 
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
> v2:
> - add device tree binding document (mdio.txt)
> - specify default reset delay in of_mdio.c instead of mdio_bus.c
> 
>  Documentation/devicetree/bindings/net/mdio.txt | 20 ++++++++++++++++++++
>  drivers/net/phy/mdio_bus.c                     | 22 ++++++++++++++++++++++
>  drivers/of/of_mdio.c                           |  7 +++++++
>  include/linux/phy.h                            |  5 +++++
>  4 files changed, 54 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/net/mdio.txt
> 
> diff --git a/Documentation/devicetree/bindings/net/mdio.txt b/Documentation/devicetree/bindings/net/mdio.txt
> new file mode 100644
> index 0000000..6e703d7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/mdio.txt
> @@ -0,0 +1,20 @@
> +Common MDIO bus properties.
> +
> +These are generic properties that can apply to any MDIO bus.
> +
> +Optional properties:
> +- reset-gpios: List of one or more GPIOs that control the RESET lines
> +  of the PHYs on that MDIO bus.
> +- reset-delay-us: RESET pulse width as per PHY datasheet.

It would be good to explicitly say that it is in uS as part of the
comment.

Also, please document that we expect a list of child nodes, one per
device on the bus. These should follow the generic phy.txt, or a
device specific binding document.

> +
> +Example :
> +

It would be good to say something like:

This example shows these optional properties, plus other properties
required for the TI Davinci MDIO driver.

Pointing this out may stop people cut/past the ti,hwmods property.

> +	davinci_mdio: ethernet@0x5c030000 {
> +		compatible = "ti,davinci_mdio";
> +		ti,hwmods = "davinci_mdio";
> +		reg = <0x5c030000 0x1000>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		reset-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>;
> +		reset-delay-us = <2>;   /* PHY datasheet states 1uS min */
> +	};

And please include at least one PHY on the bus.

Sorry for asking for so much in the documentation. That is the problem
with the documentation being missing to start with.

The code looks good now.

    Andrew
Roger Quadros April 20, 2017, 1:56 p.m. | #2
On 20/04/17 16:13, Andrew Lunn wrote:
> On Thu, Apr 20, 2017 at 11:39:20AM +0300, Roger Quadros wrote:
>> Some boards [1] leave the PHYs at an invalid state
>> during system power-up or reset thus causing unreliability
>> issues with the PHY which manifests as PHY not being detected
>> or link not functional. To fix this, these PHYs need to be RESET
>> via a GPIO connected to the PHY's RESET pin.
>>
>> Some boards have a single GPIO controlling the PHY RESET pin of all
>> PHYs on the bus whereas some others have separate GPIOs controlling
>> individual PHY RESETs.
>>
>> In both cases, the RESET de-assertion cannot be done in the PHY driver
>> as the PHY will not probe till its reset is de-asserted.
>> So do the RESET de-assertion in the MDIO bus driver.
> 
> Hi Roger
> 
> Networking patches should include in the subject line which tree they
> are for. In this case, net-next. So please make the Subject
> 
> [patch v3 net-next] .....
> 
>> [1] - am572x-idk, am571x-idk, a437x-idk
>>
>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>> ---
>> v2:
>> - add device tree binding document (mdio.txt)
>> - specify default reset delay in of_mdio.c instead of mdio_bus.c
>>
>>  Documentation/devicetree/bindings/net/mdio.txt | 20 ++++++++++++++++++++
>>  drivers/net/phy/mdio_bus.c                     | 22 ++++++++++++++++++++++
>>  drivers/of/of_mdio.c                           |  7 +++++++
>>  include/linux/phy.h                            |  5 +++++
>>  4 files changed, 54 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/net/mdio.txt
>>
>> diff --git a/Documentation/devicetree/bindings/net/mdio.txt b/Documentation/devicetree/bindings/net/mdio.txt
>> new file mode 100644
>> index 0000000..6e703d7
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/net/mdio.txt
>> @@ -0,0 +1,20 @@
>> +Common MDIO bus properties.
>> +
>> +These are generic properties that can apply to any MDIO bus.
>> +
>> +Optional properties:
>> +- reset-gpios: List of one or more GPIOs that control the RESET lines
>> +  of the PHYs on that MDIO bus.
>> +- reset-delay-us: RESET pulse width as per PHY datasheet.
> 
> It would be good to explicitly say that it is in uS as part of the
> comment.
> 
> Also, please document that we expect a list of child nodes, one per
> device on the bus. These should follow the generic phy.txt, or a
> device specific binding document.
> 
>> +
>> +Example :
>> +
> 
> It would be good to say something like:
> 
> This example shows these optional properties, plus other properties
> required for the TI Davinci MDIO driver.
> 
> Pointing this out may stop people cut/past the ti,hwmods property.
> 
>> +	davinci_mdio: ethernet@0x5c030000 {
>> +		compatible = "ti,davinci_mdio";
>> +		ti,hwmods = "davinci_mdio";
>> +		reg = <0x5c030000 0x1000>;
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +		reset-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>;
>> +		reset-delay-us = <2>;   /* PHY datasheet states 1uS min */
>> +	};
> 
> And please include at least one PHY on the bus.
> 
> Sorry for asking for so much in the documentation. That is the problem
> with the documentation being missing to start with.
> 
> The code looks good now.
> 

OK Andrew. I'll post a v3 with your suggestions.

cheers,
-roger

Patch

diff --git a/Documentation/devicetree/bindings/net/mdio.txt b/Documentation/devicetree/bindings/net/mdio.txt
new file mode 100644
index 0000000..6e703d7
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/mdio.txt
@@ -0,0 +1,20 @@ 
+Common MDIO bus properties.
+
+These are generic properties that can apply to any MDIO bus.
+
+Optional properties:
+- reset-gpios: List of one or more GPIOs that control the RESET lines
+  of the PHYs on that MDIO bus.
+- reset-delay-us: RESET pulse width as per PHY datasheet.
+
+Example :
+
+	davinci_mdio: ethernet@0x5c030000 {
+		compatible = "ti,davinci_mdio";
+		ti,hwmods = "davinci_mdio";
+		reg = <0x5c030000 0x1000>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		reset-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>;
+		reset-delay-us = <2>;   /* PHY datasheet states 1uS min */
+	};
diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index fa7d51f..b353d99 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -22,8 +22,11 @@ 
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/device.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/of_device.h>
 #include <linux/of_mdio.h>
+#include <linux/of_gpio.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/skbuff.h>
@@ -307,6 +310,7 @@  int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 {
 	struct mdio_device *mdiodev;
 	int i, err;
+	struct gpio_desc *gpiod;
 
 	if (NULL == bus || NULL == bus->name ||
 	    NULL == bus->read || NULL == bus->write)
@@ -333,6 +337,24 @@  int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 	if (bus->reset)
 		bus->reset(bus);
 
+	/* de-assert bus level PHY GPIO resets */
+	for (i = 0; i < bus->num_reset_gpios; i++) {
+		gpiod = devm_gpiod_get_index(&bus->dev, "reset", i,
+					     GPIOD_OUT_LOW);
+		if (IS_ERR(gpiod)) {
+			err = PTR_ERR(gpiod);
+			if (err != -ENOENT) {
+				pr_err("mii_bus %s couldn't get reset GPIO\n",
+				       bus->id);
+				return err;
+			}
+		} else {
+			gpiod_set_value_cansleep(gpiod, 1);
+			udelay(bus->reset_delay_us);
+			gpiod_set_value_cansleep(gpiod, 0);
+		}
+	}
+
 	for (i = 0; i < PHY_MAX_ADDR; i++) {
 		if ((bus->phy_mask & (1 << i)) == 0) {
 			struct phy_device *phydev;
diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index 0b29798..7e4c80f 100644
--- a/drivers/of/of_mdio.c
+++ b/drivers/of/of_mdio.c
@@ -22,6 +22,8 @@ 
 #include <linux/of_net.h>
 #include <linux/module.h>
 
+#define DEFAULT_GPIO_RESET_DELAY	10	/* in microseconds */
+
 MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
 MODULE_LICENSE("GPL");
 
@@ -221,6 +223,11 @@  int of_mdiobus_register(struct mii_bus *mdio, struct device_node *np)
 
 	mdio->dev.of_node = np;
 
+	/* Get bus level PHY reset GPIO details */
+	mdio->reset_delay_us = DEFAULT_GPIO_RESET_DELAY;
+	of_property_read_u32(np, "reset-delay-us", &mdio->reset_delay_us);
+	mdio->num_reset_gpios = of_gpio_named_count(np, "reset-gpios");
+
 	/* Register the MDIO bus */
 	rc = mdiobus_register(mdio);
 	if (rc)
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 43a7748..80a6574 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -217,6 +217,11 @@  struct mii_bus {
 	 * matching its address
 	 */
 	int irq[PHY_MAX_ADDR];
+
+	/* GPIO reset pulse width in uS */
+	int reset_delay_us;
+	/* Number of reset GPIOs */
+	int num_reset_gpios;
 };
 #define to_mii_bus(d) container_of(d, struct mii_bus, dev)