[PATCH] drm: i2c: tda998x: Retry fetching the EDID if it fails first time.

[PATCH] drm: i2c: tda998x: Retry fetching the EDID if it fails first time.

[Andrew Jackson]

Fetching the EDID from a connected monitor is an automated thing
with NXP TDA19988. But on some boards the fetching fails for the
first time silently without any indication that an error has occured.
More than that, subsequent fetches of the EDID succeed until the
monitor(s) are unplugged.

Add a function to validate the read EDID and retry if the block
retrieved is not valid.

Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
 drivers/gpu/drm/i2c/tda998x_drv.c |   36 ++++++++++++++++++++++++++++--------
 1 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
index d476279..025adc0 100644
--- a/drivers/gpu/drm/i2c/tda998x_drv.c
+++ b/drivers/gpu/drm/i2c/tda998x_drv.c
@@ -1066,11 +1066,36 @@ static int read_edid_block(struct tda998x_priv *priv, uint8_t *buf, int blk)
 	return 0;
 }
 
+static int
+read_validate_edid_block(struct tda998x_priv *priv, uint8_t *buf, int blk)
+{
+	bool print_bad_edid = drm_debug & DRM_UT_KMS;
+	int ret;
+	int retries = 1;
+
+	do
+	{
+		bool print_bad = print_bad_edid && (retries == 0);
+
+		ret = read_edid_block(priv, buf, blk);
+		/* Fail on I2C error */
+		if (ret)
+			break;
+
+		/* But retry checksum errored blocks */
+		if (drm_edid_block_valid(buf, blk, print_bad))
+			break;
+		else
+			ret = -EINVAL;
+	} while (retries-- > 0);
+
+	return ret;
+}
+
 static uint8_t *do_get_edid(struct tda998x_priv *priv)
 {
 	int j, valid_extensions = 0;
 	uint8_t *block, *new;
-	bool print_bad_edid = drm_debug & DRM_UT_KMS;
 
 	if ((block = kmalloc(EDID_LENGTH, GFP_KERNEL)) == NULL)
 		return NULL;
@@ -1079,10 +1104,7 @@ static uint8_t *do_get_edid(struct tda998x_priv *priv)
 		reg_clear(priv, REG_TX4, TX4_PD_RAM);
 
 	/* base block fetch */
-	if (read_edid_block(priv, block, 0))
-		goto fail;
-
-	if (!drm_edid_block_valid(block, 0, print_bad_edid))
+	if (read_validate_edid_block(priv, block, 0))
 		goto fail;
 
 	/* if there's no extensions, we're done */
@@ -1096,10 +1118,8 @@ static uint8_t *do_get_edid(struct tda998x_priv *priv)
 
 	for (j = 1; j <= block[0x7e]; j++) {
 		uint8_t *ext_block = block + (valid_extensions + 1) * EDID_LENGTH;
-		if (read_edid_block(priv, ext_block, j))
-			goto fail;
 
-		if (!drm_edid_block_valid(ext_block, j, print_bad_edid))
+		if (read_validate_edid_block(priv, ext_block, j))
 			goto fail;
 
 		valid_extensions++;
-- 
1.7.1

[PATCH] drm: i2c: tda998x: Retry fetching the EDID if it fails first time.

[Jean-Francois Moine]

On Tue, 18 Nov 2014 17:41:26 +0000
Andrew Jackson <Andrew.Jackson@arm.com> wrote:

> Fetching the EDID from a connected monitor is an automated thing
> with NXP TDA19988. But on some boards the fetching fails for the
> first time silently without any indication that an error has occured.
> More than that, subsequent fetches of the EDID succeed until the
> monitor(s) are unplugged.
> 
> Add a function to validate the read EDID and retry if the block
> retrieved is not valid.
> 
> Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

It seems that your patch is deprecated by Laurent Pinchart's
	[PATCH] drm: tda998x: Use drm_do_get_edid()
http://lists.freedesktop.org/archives/dri-devel/2014-November/072906.html

-- 
Ken ar c'henta?	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

[PATCH] drm: i2c: tda998x: Retry fetching the EDID if it fails first time.

[Andrew Jackson]

On 11/28/14 08:19, Jean-Francois Moine wrote:
> On Tue, 18 Nov 2014 17:41:26 +0000
> Andrew Jackson <Andrew.Jackson@arm.com> wrote:
> 
>> Fetching the EDID from a connected monitor is an automated thing
>> with NXP TDA19988. But on some boards the fetching fails for the
>> first time silently without any indication that an error has occured.
>> More than that, subsequent fetches of the EDID succeed until the
>> monitor(s) are unplugged.
>>
>> Add a function to validate the read EDID and retry if the block
>> retrieved is not valid.
>>
>> Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com>
>> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
> 
> It seems that your patch is deprecated by Laurent Pinchart's
> 	[PATCH] drm: tda998x: Use drm_do_get_edid()
> http://lists.freedesktop.org/archives/dri-devel/2014-November/072906.html
> 

Thank you for the heads-up, I'd not seen that.  I'll consider how my patch might be modified to suit the new infrastructure.

    Andrew

[PATCH] drm: i2c: tda998x: Retry fetching the EDID if it fails first time.

[Jean-Francois Moine]

On Fri, 28 Nov 2014 09:02:39 +0000
Andrew Jackson <Andrew.Jackson@arm.com> wrote:

> > It seems that your patch is deprecated by Laurent Pinchart's
> > 	[PATCH] drm: tda998x: Use drm_do_get_edid()
> > http://lists.freedesktop.org/archives/dri-devel/2014-November/072906.html
> >   
> 
> Thank you for the heads-up, I'd not seen that.  I'll consider how my patch might be modified to suit the new infrastructure.

You don't need any patch: drm_do_get_edid() already loops on reading
the EDID.

-- 
Ken ar c'henta?	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

[PATCH] drm: i2c: tda998x: Retry fetching the EDID if it fails first time.

[Andrew Jackson]

On 11/29/14 10:41, Jean-Francois Moine wrote:
> On Fri, 28 Nov 2014 09:02:39 +0000
> Andrew Jackson <Andrew.Jackson@arm.com> wrote:
> 
>>> It seems that your patch is deprecated by Laurent Pinchart's
>>> 	[PATCH] drm: tda998x: Use drm_do_get_edid()
>>> http://lists.freedesktop.org/archives/dri-devel/2014-November/072906.html
>>>   
>>
>> Thank you for the heads-up, I'd not seen that.  I'll consider how my patch might be modified to suit the new infrastructure.
> 
> You don't need any patch: drm_do_get_edid() already loops on reading
> the EDID.
> 

Thank you again: that saves me work!

   Andrew