[v2] w1: masters: omap_hdq: Add support for 1-wire mode

This patches makes following changes to omap_hdq driver
 - Enable 1-wire mode.
 - Implement w1_triplet callback to facilitate search rom
   procedure and auto detection of 1-wire slaves.
 - Proper enabling and disabling of interrupt.
 - Cleanups (formatting and return value checks).

HDQ mode remains unchanged.

Signed-off-by: Vignesh R <vigneshr@ti.com>
---

v2:
 * report error if RX/TX_COMPLETE times out.

 Documentation/devicetree/bindings/w1/omap-hdq.txt |   7 +-
 Documentation/w1/masters/omap-hdq                 |   6 +
 drivers/w1/masters/omap_hdq.c                     | 224 ++++++++++++++++++----
 3 files changed, 203 insertions(+), 34 deletions(-)

On Monday 18 May 2015 05:39 PM, Vignesh R wrote:
> This patches makes following changes to omap_hdq driver
>  - Enable 1-wire mode.
>  - Implement w1_triplet callback to facilitate search rom
>    procedure and auto detection of 1-wire slaves.
>  - Proper enabling and disabling of interrupt.
>  - Cleanups (formatting and return value checks).
> 
> HDQ mode remains unchanged.
> 
> Signed-off-by: Vignesh R <vigneshr@ti.com>
> ---

Gentle ping...

> 
> v2:
>  * report error if RX/TX_COMPLETE times out.
> 
>  Documentation/devicetree/bindings/w1/omap-hdq.txt |   7 +-
>  Documentation/w1/masters/omap-hdq                 |   6 +
>  drivers/w1/masters/omap_hdq.c                     | 224 ++++++++++++++++++----
>  3 files changed, 203 insertions(+), 34 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/w1/omap-hdq.txt b/Documentation/devicetree/bindings/w1/omap-hdq.txt
> index fef794741bd1..913c5f91a0f9 100644
> --- a/Documentation/devicetree/bindings/w1/omap-hdq.txt
> +++ b/Documentation/devicetree/bindings/w1/omap-hdq.txt
> @@ -1,11 +1,15 @@
>  * OMAP HDQ One wire bus master controller
>  
>  Required properties:
> -- compatible : should be "ti,omap3-1w"
> +- compatible : should be "ti,omap3-1w" or "ti,am4372-hdq"
>  - reg : Address and length of the register set for the device
>  - interrupts : interrupt line.
>  - ti,hwmods : "hdq1w"
>  
> +Optional properties:
> +- ti,mode: should be "hdq": HDQ mode  "1w": one-wire mode.
> +	   If not specified HDQ mode is implied.
> +
>  Example:
>  
>  - From omap3.dtsi
> @@ -14,4 +18,5 @@ Example:
>  	reg = <0x480b2000 0x1000>;
>  	interrupts = <58>;
>  	ti,hwmods = "hdq1w";
> +	ti,mode = "hdq";
>    };
> diff --git a/Documentation/w1/masters/omap-hdq b/Documentation/w1/masters/omap-hdq
> index 884dc284b215..234522709a5f 100644
> --- a/Documentation/w1/masters/omap-hdq
> +++ b/Documentation/w1/masters/omap-hdq
> @@ -44,3 +44,9 @@ e.g:
>  insmod omap_hdq.ko W1_ID=2
>  inamod w1_bq27000.ko F_ID=2
>  
> +The driver also supports 1-wire mode. In this mode, there is no need to
> +pass slave ID as parameter. The driver will auto-detect slaves connected
> +to the bus using SEARCH_ROM procedure. 1-wire mode can be selected by
> +setting "ti,mode" property to "1w" in DT (see
> +Documentation/devicetree/bindings/w1/omap-hdq.txt for more details).
> +By default driver is in HDQ mode.
> diff --git a/drivers/w1/masters/omap_hdq.c b/drivers/w1/masters/omap_hdq.c
> index e7d448963a24..0e2f43bccf1f 100644
> --- a/drivers/w1/masters/omap_hdq.c
> +++ b/drivers/w1/masters/omap_hdq.c
> @@ -17,6 +17,7 @@
>  #include <linux/io.h>
>  #include <linux/sched.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/of.h>
>  
>  #include "../w1.h"
>  #include "../w1_int.h"
> @@ -27,21 +28,23 @@
>  #define OMAP_HDQ_TX_DATA			0x04
>  #define OMAP_HDQ_RX_DATA			0x08
>  #define OMAP_HDQ_CTRL_STATUS			0x0c
> -#define OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK	(1<<6)
> -#define OMAP_HDQ_CTRL_STATUS_CLOCKENABLE	(1<<5)
> -#define OMAP_HDQ_CTRL_STATUS_GO			(1<<4)
> -#define OMAP_HDQ_CTRL_STATUS_INITIALIZATION	(1<<2)
> -#define OMAP_HDQ_CTRL_STATUS_DIR		(1<<1)
> -#define OMAP_HDQ_CTRL_STATUS_MODE		(1<<0)
> +#define OMAP_HDQ_CTRL_STATUS_SINGLE		BIT(7)
> +#define OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK	BIT(6)
> +#define OMAP_HDQ_CTRL_STATUS_CLOCKENABLE	BIT(5)
> +#define OMAP_HDQ_CTRL_STATUS_GO                 BIT(4)
> +#define OMAP_HDQ_CTRL_STATUS_PRESENCE		BIT(3)
> +#define OMAP_HDQ_CTRL_STATUS_INITIALIZATION	BIT(2)
> +#define OMAP_HDQ_CTRL_STATUS_DIR		BIT(1)
>  #define OMAP_HDQ_INT_STATUS			0x10
> -#define OMAP_HDQ_INT_STATUS_TXCOMPLETE		(1<<2)
> -#define OMAP_HDQ_INT_STATUS_RXCOMPLETE		(1<<1)
> -#define OMAP_HDQ_INT_STATUS_TIMEOUT		(1<<0)
> +#define OMAP_HDQ_INT_STATUS_TXCOMPLETE		BIT(2)
> +#define OMAP_HDQ_INT_STATUS_RXCOMPLETE		BIT(1)
> +#define OMAP_HDQ_INT_STATUS_TIMEOUT		BIT(0)
>  #define OMAP_HDQ_SYSCONFIG			0x14
> -#define OMAP_HDQ_SYSCONFIG_SOFTRESET		(1<<1)
> -#define OMAP_HDQ_SYSCONFIG_AUTOIDLE		(1<<0)
> +#define OMAP_HDQ_SYSCONFIG_SOFTRESET		BIT(1)
> +#define OMAP_HDQ_SYSCONFIG_AUTOIDLE		BIT(0)
> +#define OMAP_HDQ_SYSCONFIG_NOIDLE		0x0
>  #define OMAP_HDQ_SYSSTATUS			0x18
> -#define OMAP_HDQ_SYSSTATUS_RESETDONE		(1<<0)
> +#define OMAP_HDQ_SYSSTATUS_RESETDONE		BIT(0)
>  
>  #define OMAP_HDQ_FLAG_CLEAR			0
>  #define OMAP_HDQ_FLAG_SET			1
> @@ -67,6 +70,10 @@ struct hdq_data {
>  	 * the data wrire or read.
>  	 */
>  	int			init_trans;
> +	int                     rrw;
> +	/* mode: 0-HDQ 1-W1 */
> +	int                     mode;
> +
>  };
>  
>  static int omap_hdq_probe(struct platform_device *pdev);
> @@ -74,6 +81,7 @@ static int omap_hdq_remove(struct platform_device *pdev);
>  
>  static const struct of_device_id omap_hdq_dt_ids[] = {
>  	{ .compatible = "ti,omap3-1w" },
> +	{ .compatible = "ti,am4372-hdq" },
>  	{}
>  };
>  MODULE_DEVICE_TABLE(of, omap_hdq_dt_ids);
> @@ -90,15 +98,12 @@ static struct platform_driver omap_hdq_driver = {
>  static u8 omap_w1_read_byte(void *_hdq);
>  static void omap_w1_write_byte(void *_hdq, u8 byte);
>  static u8 omap_w1_reset_bus(void *_hdq);
> -static void omap_w1_search_bus(void *_hdq, struct w1_master *master_dev,
> -		u8 search_type,	w1_slave_found_callback slave_found);
>  
>  
>  static struct w1_bus_master omap_w1_master = {
>  	.read_byte	= omap_w1_read_byte,
>  	.write_byte	= omap_w1_write_byte,
>  	.reset_bus	= omap_w1_reset_bus,
> -	.search		= omap_w1_search_bus,
>  };
>  
>  /* HDQ register I/O routines */
> @@ -122,6 +127,15 @@ static inline u8 hdq_reg_merge(struct hdq_data *hdq_data, u32 offset,
>  	return new_val;
>  }
>  
> +static void hdq_disable_interrupt(struct hdq_data *hdq_data, u32 offset,
> +				  u32 mask)
> +{
> +	u32 ie;
> +
> +	ie = readl(hdq_data->hdq_base + offset);
> +	writel(ie & mask, hdq_data->hdq_base + offset);
> +}
> +
>  /*
>   * Wait for one or more bits in flag change.
>   * HDQ_FLAG_SET: wait until any bit in the flag is set.
> @@ -229,13 +243,7 @@ static irqreturn_t hdq_isr(int irq, void *_hdq)
>  	return IRQ_HANDLED;
>  }
>  
> -/* HDQ Mode: always return success */
> -static u8 omap_w1_reset_bus(void *_hdq)
> -{
> -	return 0;
> -}
> -
> -/* W1 search callback function */
> +/* W1 search callback function  in HDQ mode */
>  static void omap_w1_search_bus(void *_hdq, struct w1_master *master_dev,
>  		u8 search_type, w1_slave_found_callback slave_found)
>  {
> @@ -262,9 +270,10 @@ static int _omap_hdq_reset(struct hdq_data *hdq_data)
>  	int ret;
>  	u8 tmp_status;
>  
> -	hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG, OMAP_HDQ_SYSCONFIG_SOFTRESET);
> +	hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG,
> +		    OMAP_HDQ_SYSCONFIG_SOFTRESET);
>  	/*
> -	 * Select HDQ mode & enable clocks.
> +	 * Select HDQ/1W mode & enable clocks.
>  	 * It is observed that INT flags can't be cleared via a read and GO/INIT
>  	 * won't return to zero if interrupt is disabled. So we always enable
>  	 * interrupt.
> @@ -282,7 +291,8 @@ static int _omap_hdq_reset(struct hdq_data *hdq_data)
>  	else {
>  		hdq_reg_out(hdq_data, OMAP_HDQ_CTRL_STATUS,
>  			OMAP_HDQ_CTRL_STATUS_CLOCKENABLE |
> -			OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK);
> +			OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK |
> +			hdq_data->mode);
>  		hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG,
>  			OMAP_HDQ_SYSCONFIG_AUTOIDLE);
>  	}
> @@ -334,6 +344,18 @@ static int omap_hdq_break(struct hdq_data *hdq_data)
>  		ret = -ETIMEDOUT;
>  		goto out;
>  	}
> +
> +	/*
> +	 * check for the presence detect bit to get
> +	 * set to show that the slave is responding
> +	 */
> +	if (!(hdq_reg_in(hdq_data, OMAP_HDQ_CTRL_STATUS) &
> +			OMAP_HDQ_CTRL_STATUS_PRESENCE)) {
> +		dev_dbg(hdq_data->dev, "Presence bit not set\n");
> +		ret = -ETIMEDOUT;
> +		goto out;
> +	}
> +
>  	/*
>  	 * wait for both INIT and GO bits rerurn to zero.
>  	 * zero wait time expected for interrupt mode.
> @@ -368,6 +390,8 @@ static int hdq_read_byte(struct hdq_data *hdq_data, u8 *val)
>  		goto out;
>  	}
>  
> +	hdq_data->hdq_irqstatus = 0;
> +
>  	if (!(hdq_data->hdq_irqstatus & OMAP_HDQ_INT_STATUS_RXCOMPLETE)) {
>  		hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS,
>  			OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_GO,
> @@ -400,7 +424,7 @@ rtn:
>  
>  }
>  
> -/* Enable clocks and set the controller to HDQ mode */
> +/* Enable clocks and set the controller to HDQ/1W mode */
>  static int omap_hdq_get(struct hdq_data *hdq_data)
>  {
>  	int ret = 0;
> @@ -422,7 +446,7 @@ static int omap_hdq_get(struct hdq_data *hdq_data)
>  
>  			pm_runtime_get_sync(hdq_data->dev);
>  
> -			/* make sure HDQ is out of reset */
> +			/* make sure HDQ/1W is out of reset */
>  			if (!(hdq_reg_in(hdq_data, OMAP_HDQ_SYSSTATUS) &
>  				OMAP_HDQ_SYSSTATUS_RESETDONE)) {
>  				ret = _omap_hdq_reset(hdq_data);
> @@ -430,12 +454,13 @@ static int omap_hdq_get(struct hdq_data *hdq_data)
>  					/* back up the count */
>  					hdq_data->hdq_usecount--;
>  			} else {
> -				/* select HDQ mode & enable clocks */
> +				/* select HDQ/1W mode & enable clocks */
>  				hdq_reg_out(hdq_data, OMAP_HDQ_CTRL_STATUS,
>  					OMAP_HDQ_CTRL_STATUS_CLOCKENABLE |
> -					OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK);
> +					OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK |
> +					hdq_data->mode);
>  				hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG,
> -					OMAP_HDQ_SYSCONFIG_AUTOIDLE);
> +					OMAP_HDQ_SYSCONFIG_NOIDLE);
>  				hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
>  			}
>  		}
> @@ -456,6 +481,8 @@ static int omap_hdq_put(struct hdq_data *hdq_data)
>  	if (ret < 0)
>  		return -EINTR;
>  
> +	hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG,
> +		    OMAP_HDQ_SYSCONFIG_AUTOIDLE);
>  	if (0 == hdq_data->hdq_usecount) {
>  		dev_dbg(hdq_data->dev, "attempt to decrement use count"
>  			" when it is zero");
> @@ -471,6 +498,100 @@ static int omap_hdq_put(struct hdq_data *hdq_data)
>  	return ret;
>  }
>  
> +/*
> + * W1 triplet callback function - used for searching ROM addresses.
> + * Registered only when controller is in 1-wire mode.
> + */
> +static u8 omap_w1_triplet(void *_hdq, u8 bdir)
> +{
> +	u8 id_bit, comp_bit;
> +	int err;
> +	u8 ret = 0x3; /* no slaves responded */
> +	struct hdq_data *hdq_data = _hdq;
> +	u8 ctrl = OMAP_HDQ_CTRL_STATUS_SINGLE | OMAP_HDQ_CTRL_STATUS_GO |
> +		  OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK;
> +	u8 mask = ctrl | OMAP_HDQ_CTRL_STATUS_DIR;
> +
> +	omap_hdq_get(_hdq);
> +
> +	err = mutex_lock_interruptible(&hdq_data->hdq_mutex);
> +	if (err < 0) {
> +		dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
> +		goto rtn;
> +	}
> +
> +	hdq_data->hdq_irqstatus = 0;
> +	/* read id_bit */
> +	hdq_reg_merge(_hdq, OMAP_HDQ_CTRL_STATUS,
> +		      ctrl | OMAP_HDQ_CTRL_STATUS_DIR, mask);
> +	err = wait_event_timeout(hdq_wait_queue,
> +				 (hdq_data->hdq_irqstatus
> +				  & OMAP_HDQ_INT_STATUS_RXCOMPLETE),
> +				 OMAP_HDQ_TIMEOUT);
> +	if (err == 0) {
> +		dev_dbg(hdq_data->dev, "RX wait elapsed\n");
> +		goto out;
> +	}
> +	id_bit = (hdq_reg_in(_hdq, OMAP_HDQ_RX_DATA) & 0x01);
> +
> +	hdq_data->hdq_irqstatus = 0;
> +	/* read comp_bit */
> +	hdq_reg_merge(_hdq, OMAP_HDQ_CTRL_STATUS,
> +		      ctrl | OMAP_HDQ_CTRL_STATUS_DIR, mask);
> +	err = wait_event_timeout(hdq_wait_queue,
> +				 (hdq_data->hdq_irqstatus
> +				  & OMAP_HDQ_INT_STATUS_RXCOMPLETE),
> +				 OMAP_HDQ_TIMEOUT);
> +	if (err == 0) {
> +		dev_dbg(hdq_data->dev, "RX wait elapsed\n");
> +		goto out;
> +	}
> +	comp_bit = (hdq_reg_in(_hdq, OMAP_HDQ_RX_DATA) & 0x01);
> +
> +	if (id_bit && comp_bit) {
> +		ret = 0x03;  /* no slaves responded */
> +		goto out;
> +	}
> +	if (!id_bit && !comp_bit) {
> +		/* Both bits are valid, take the direction given */
> +		ret = bdir ? 0x04 : 0;
> +	} else {
> +		/* Only one bit is valid, take that direction */
> +		bdir = id_bit;
> +		ret = id_bit ? 0x05 : 0x02;
> +	}
> +
> +	/* write bdir bit */
> +	hdq_reg_out(_hdq, OMAP_HDQ_TX_DATA, bdir);
> +	hdq_reg_merge(_hdq, OMAP_HDQ_CTRL_STATUS, ctrl, mask);
> +	err = wait_event_timeout(hdq_wait_queue,
> +				 (hdq_data->hdq_irqstatus
> +				  & OMAP_HDQ_INT_STATUS_TXCOMPLETE),
> +				 OMAP_HDQ_TIMEOUT);
> +	if (err == 0) {
> +		dev_dbg(hdq_data->dev, "TX wait elapsed\n");
> +		goto out;
> +	}
> +
> +	hdq_reg_merge(_hdq, OMAP_HDQ_CTRL_STATUS, 0,
> +		      OMAP_HDQ_CTRL_STATUS_SINGLE);
> +
> +out:
> +	mutex_unlock(&hdq_data->hdq_mutex);
> +rtn:
> +	omap_hdq_put(_hdq);
> +	return ret;
> +}
> +
> +/* reset callback */
> +static u8 omap_w1_reset_bus(void *_hdq)
> +{
> +	omap_hdq_get(_hdq);
> +	omap_hdq_break(_hdq);
> +	omap_hdq_put(_hdq);
> +	return 0;
> +}
> +
>  /* Read a byte of data from the device */
>  static u8 omap_w1_read_byte(void *_hdq)
>  {
> @@ -478,6 +599,10 @@ static u8 omap_w1_read_byte(void *_hdq)
>  	u8 val = 0;
>  	int ret;
>  
> +	/* First write to initialize the transfer */
> +	if (hdq_data->init_trans == 0)
> +		omap_hdq_get(hdq_data);
> +
>  	ret = hdq_read_byte(hdq_data, &val);
>  	if (ret) {
>  		ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
> @@ -491,6 +616,10 @@ static u8 omap_w1_read_byte(void *_hdq)
>  		return -1;
>  	}
>  
> +	hdq_disable_interrupt(hdq_data, OMAP_HDQ_CTRL_STATUS,
> +			      ~OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK);
> +	hdq_data->hdq_usecount = 0;
> +
>  	/* Write followed by a read, release the module */
>  	if (hdq_data->init_trans) {
>  		ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
> @@ -517,6 +646,14 @@ static void omap_w1_write_byte(void *_hdq, u8 byte)
>  	if (hdq_data->init_trans == 0)
>  		omap_hdq_get(hdq_data);
>  
> +	/*
> +	 * We need to reset the slave before
> +	 * issuing the SKIP ROM command, else
> +	 * the slave will not work.
> +	 */
> +	if (byte == W1_SKIP_ROM)
> +		omap_hdq_break(hdq_data);
> +
>  	ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
>  	if (ret < 0) {
>  		dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
> @@ -551,6 +688,7 @@ static int omap_hdq_probe(struct platform_device *pdev)
>  	struct resource *res;
>  	int ret, irq;
>  	u8 rev;
> +	const char *mode;
>  
>  	hdq_data = devm_kzalloc(dev, sizeof(*hdq_data), GFP_KERNEL);
>  	if (!hdq_data) {
> @@ -567,10 +705,21 @@ static int omap_hdq_probe(struct platform_device *pdev)
>  		return PTR_ERR(hdq_data->hdq_base);
>  
>  	hdq_data->hdq_usecount = 0;
> +	hdq_data->rrw = 0;
>  	mutex_init(&hdq_data->hdq_mutex);
>  
>  	pm_runtime_enable(&pdev->dev);
> -	pm_runtime_get_sync(&pdev->dev);
> +	ret = pm_runtime_get_sync(&pdev->dev);
> +	if (ret < 0) {
> +		dev_dbg(&pdev->dev, "pm_runtime_get_sync failed\n");
> +		goto err_w1;
> +	}
> +
> +	ret = _omap_hdq_reset(hdq_data);
> +	if (ret) {
> +		dev_dbg(&pdev->dev, "reset failed\n");
> +		return -EINVAL;
> +	}
>  
>  	rev = hdq_reg_in(hdq_data, OMAP_HDQ_REVISION);
>  	dev_info(&pdev->dev, "OMAP HDQ Hardware Rev %c.%c. Driver in %s mode\n",
> @@ -594,6 +743,15 @@ static int omap_hdq_probe(struct platform_device *pdev)
>  
>  	pm_runtime_put_sync(&pdev->dev);
>  
> +	ret = of_property_read_string(pdev->dev.of_node, "ti,mode", &mode);
> +	if (ret < 0 || !strcmp(mode, "hdq")) {
> +		hdq_data->mode = 0;
> +		omap_w1_master.search = omap_w1_search_bus;
> +	} else {
> +		hdq_data->mode = 1;
> +		omap_w1_master.triplet = omap_w1_triplet;
> +	}
> +
>  	omap_w1_master.data = hdq_data;
>  
>  	ret = w1_add_master_device(&omap_w1_master);
> @@ -635,8 +793,8 @@ static int omap_hdq_remove(struct platform_device *pdev)
>  module_platform_driver(omap_hdq_driver);
>  
>  module_param(w1_id, int, S_IRUSR);
> -MODULE_PARM_DESC(w1_id, "1-wire id for the slave detection");
> +MODULE_PARM_DESC(w1_id, "1-wire id for the slave detection in HDQ mode");
>  
>  MODULE_AUTHOR("Texas Instruments");
> -MODULE_DESCRIPTION("HDQ driver Library");
> +MODULE_DESCRIPTION("HDQ-1W driver Library");
>  MODULE_LICENSE("GPL");
> 
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Hi

25.05.2015, 08:15, "Vignesh R" <vigneshr@ti.com>:
>>  HDQ mode remains unchanged.
>>
>>  Signed-off-by: Vignesh R <vigneshr@ti.com>

I have no experience with omap_hdq platform, but there are quite a few questions
related to IO - you never check whether write was successful or read returned actually
valid data, is it ok? I mean is it correct to assume that read can not return 0xff for example
and it is a sign that something is wrong, or this can not happen?

As for me, I have no objection, but this patch must go via omap tree imo.
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Hi,

On Thursday 11 June 2015 09:04 PM, Evgeniy Polyakov wrote:
> Hi
> 
> 25.05.2015, 08:15, "Vignesh R" <vigneshr@ti.com>:
>>>  HDQ mode remains unchanged.
>>>
>>>  Signed-off-by: Vignesh R <vigneshr@ti.com>
> 
> I have no experience with omap_hdq platform, but there are quite a few questions
> related to IO - you never check whether write was successful or read returned actually
> valid data, is it ok? I mean is it correct to assume that read can not return 0xff for example
> and it is a sign that something is wrong, or this can not happen?
> 

Referring to AM437x TRM SPRUHL7C
(www.ti.com/lit/ug/spruhl7c/spruhl7c.pdf) section 23.3.5.4, Successful
or failed completion is not indicated for write operation, so there is
no way to verify whether write succeeded (though TX_COMPLETE interrupt
bit is set on transaction completion). But, as for as read operation is
concerned, the TRM says, if RX_COMPLETE bit is set, then read is
successful and I think that implies valid data is present in RX reg. My
patch does look for TX/RX_COMPLETE bits to be set after write/read
operations.

> As for me, I have no objection, but this patch must go via omap tree imo.
> 

Andrew Morton has already picked this patch (its on linux-next).
Although he has a minor comment on use of mutex_lock_interruptible. But
that comment applies to many places in the existing driver code. I plan
to cleanup all those mutex calls in near future.

Regards
Vignesh
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html