All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state
@ 2018-04-16 15:53 Imre Deak
  2018-04-16 17:43 ` ✓ Fi.CI.BAT: success for " Patchwork
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Imre Deak @ 2018-04-16 15:53 UTC (permalink / raw)
  To: dri-devel, intel-gfx

LSPCON adapters in low-power state may ignore the first I2C write during
TMDS output buffer enabling, resulting in a blank screen even with an
otherwise enabled pipe. Fix this by reading back and validating the
written value a few times.

The problem was noticed on GLK machines with an onboard LSPCON adapter
after entering/exiting DC5 power state. Doing an I2C read of the adapter
ID as the first transaction - instead of the I2C write to enable the
TMDS buffers - returns the correct value. Based on this we assume that
the transaction itself is sent properly, it's only the adapter that is
not ready for some reason to accept this first write after waking from
low-power state. In my case the second I2C write attempt always
succeeded.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105854
Cc: Clinton Taylor <clinton.a.taylor@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/drm_dp_dual_mode_helper.c | 39 +++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
index 02a50929af67..e7f4fe2848a5 100644
--- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
+++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
@@ -350,19 +350,44 @@ int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type,
 {
 	uint8_t tmds_oen = enable ? 0 : DP_DUAL_MODE_TMDS_DISABLE;
 	ssize_t ret;
+	int retry;
 
 	if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
 		return 0;
 
-	ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
-				     &tmds_oen, sizeof(tmds_oen));
-	if (ret) {
-		DRM_DEBUG_KMS("Failed to %s TMDS output buffers\n",
-			      enable ? "enable" : "disable");
-		return ret;
+	/*
+	 * LSPCON adapters in low-power state may ignore the first write, so
+	 * read back and verify the written value a few times.
+	 */
+	for (retry = 0; retry < 3; retry++) {
+		uint8_t tmp;
+
+		ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
+					     &tmds_oen, sizeof(tmds_oen));
+		if (ret) {
+			DRM_DEBUG_KMS("Failed to %s TMDS output buffers (%d attempts)\n",
+				      enable ? "enable" : "disable",
+				      retry + 1);
+			return ret;
+		}
+
+		ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
+					    &tmp, sizeof(tmp));
+		if (ret) {
+			DRM_DEBUG_KMS("I2C read failed during TMDS output buffer %s (%d attempts)\n",
+				      enable ? "enabling" : "disabling",
+				      retry + 1);
+			return ret;
+		}
+
+		if (tmp == tmds_oen)
+			return 0;
 	}
 
-	return 0;
+	DRM_DEBUG_KMS("I2C write value mismatch during TMDS output buffer %s\n",
+		      enable ? "enabling" : "disabling");
+
+	return -EIO;
 }
 EXPORT_SYMBOL(drm_dp_dual_mode_set_tmds_output);
 
-- 
2.13.2

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

^ permalink raw reply related	[flat|nested] 6+ messages in thread

* ✓ Fi.CI.BAT: success for drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state
  2018-04-16 15:53 [PATCH] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state Imre Deak
@ 2018-04-16 17:43 ` Patchwork
  2018-04-16 20:44 ` ✓ Fi.CI.IGT: " Patchwork
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 6+ messages in thread
From: Patchwork @ 2018-04-16 17:43 UTC (permalink / raw)
  To: Imre Deak; +Cc: intel-gfx

== Series Details ==

Series: drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state
URL   : https://patchwork.freedesktop.org/series/41759/
State : success

== Summary ==

= CI Bug Log - changes from CI_DRM_4057 -> Patchwork_8697 =

== Summary - WARNING ==

  Minor unknown changes coming with Patchwork_8697 need to be verified
  manually.
  
  If you think the reported changes have nothing to do with the changes
  introduced in Patchwork_8697, please notify your bug team to allow them
  to document this new failure mode, which will reduce false positives in CI.

  External URL: https://patchwork.freedesktop.org/api/1.0/series/41759/revisions/1/mbox/

== Possible new issues ==

  Here are the unknown changes that may have been introduced in Patchwork_8697:

  === IGT changes ===

    ==== Warnings ====

    igt@gem_exec_gttfill@basic:
      fi-pnv-d510:        SKIP -> PASS

    
== Known issues ==

  Here are the changes found in Patchwork_8697 that come from known issues:

  === IGT changes ===

    ==== Issues hit ====

    igt@debugfs_test@read_all_entries:
      fi-snb-2520m:       PASS -> INCOMPLETE (fdo#103713)

    igt@gem_mmap_gtt@basic-small-bo-tiledx:
      fi-gdg-551:         PASS -> FAIL (fdo#102575)

    
    ==== Possible fixes ====

    igt@kms_pipe_crc_basic@suspend-read-crc-pipe-b:
      fi-ivb-3520m:       DMESG-WARN (fdo#106084) -> PASS +1

    
  fdo#102575 https://bugs.freedesktop.org/show_bug.cgi?id=102575
  fdo#103713 https://bugs.freedesktop.org/show_bug.cgi?id=103713
  fdo#106084 https://bugs.freedesktop.org/show_bug.cgi?id=106084


== Participating hosts (36 -> 33) ==

  Missing    (3): fi-ctg-p8600 fi-ilk-m540 fi-skl-6700hq 


== Build changes ==

    * Linux: CI_DRM_4057 -> Patchwork_8697

  CI_DRM_4057: ac35105865ed2d4d9676fdb4752798b047fb126a @ git://anongit.freedesktop.org/gfx-ci/linux
  IGT_4432: 8b77704db49167f7ebfd1c470d9c129d3b862cb6 @ git://anongit.freedesktop.org/xorg/app/intel-gpu-tools
  Patchwork_8697: 5c78b9dc05bc38b3d767abc50a33b889e7cfd29d @ git://anongit.freedesktop.org/gfx-ci/linux
  piglit_4432: 93b35926a150e318439d2505901288594b3548f5 @ git://anongit.freedesktop.org/piglit


== Linux commits ==

5c78b9dc05bc drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_8697/issues.html
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

^ permalink raw reply	[flat|nested] 6+ messages in thread

* ✓ Fi.CI.IGT: success for drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state
  2018-04-16 15:53 [PATCH] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state Imre Deak
  2018-04-16 17:43 ` ✓ Fi.CI.BAT: success for " Patchwork
@ 2018-04-16 20:44 ` Patchwork
  2018-04-17  0:14 ` [PATCH] " Clint Taylor
  2018-04-17 17:57 ` Ville Syrjälä
  3 siblings, 0 replies; 6+ messages in thread
From: Patchwork @ 2018-04-16 20:44 UTC (permalink / raw)
  To: Imre Deak; +Cc: intel-gfx

== Series Details ==

Series: drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state
URL   : https://patchwork.freedesktop.org/series/41759/
State : success

== Summary ==

= CI Bug Log - changes from CI_DRM_4057_full -> Patchwork_8697_full =

== Summary - WARNING ==

  Minor unknown changes coming with Patchwork_8697_full need to be verified
  manually.
  
  If you think the reported changes have nothing to do with the changes
  introduced in Patchwork_8697_full, please notify your bug team to allow them
  to document this new failure mode, which will reduce false positives in CI.

  External URL: https://patchwork.freedesktop.org/api/1.0/series/41759/revisions/1/mbox/

== Possible new issues ==

  Here are the unknown changes that may have been introduced in Patchwork_8697_full:

  === IGT changes ===

    ==== Warnings ====

    igt@kms_frontbuffer_tracking@fbc-1p-offscren-pri-shrfb-draw-mmap-cpu:
      shard-snb:          SKIP -> PASS +1

    
== Known issues ==

  Here are the changes found in Patchwork_8697_full that come from known issues:

  === IGT changes ===

    ==== Issues hit ====

    igt@kms_flip@2x-blocking-wf_vblank:
      shard-hsw:          PASS -> FAIL (fdo#103928)

    igt@kms_flip@2x-plain-flip-ts-check-interruptible:
      shard-hsw:          PASS -> FAIL (fdo#100368)

    igt@kms_flip@modeset-vs-vblank-race-interruptible:
      shard-hsw:          PASS -> FAIL (fdo#103060)

    igt@kms_plane_lowres@pipe-c-tiling-yf:
      shard-apl:          PASS -> FAIL (fdo#103166)

    igt@perf_pmu@rc6-runtime-pm-long:
      shard-apl:          PASS -> FAIL (fdo#105010)

    
    ==== Possible fixes ====

    igt@kms_mmio_vs_cs_flip@setcrtc_vs_cs_flip:
      shard-kbl:          DMESG-WARN (fdo#105602, fdo#103558) -> PASS +10

    igt@perf@blocking:
      shard-hsw:          FAIL (fdo#102252) -> PASS

    
  fdo#100368 https://bugs.freedesktop.org/show_bug.cgi?id=100368
  fdo#102252 https://bugs.freedesktop.org/show_bug.cgi?id=102252
  fdo#103060 https://bugs.freedesktop.org/show_bug.cgi?id=103060
  fdo#103166 https://bugs.freedesktop.org/show_bug.cgi?id=103166
  fdo#103558 https://bugs.freedesktop.org/show_bug.cgi?id=103558
  fdo#103928 https://bugs.freedesktop.org/show_bug.cgi?id=103928
  fdo#105010 https://bugs.freedesktop.org/show_bug.cgi?id=105010
  fdo#105602 https://bugs.freedesktop.org/show_bug.cgi?id=105602


== Participating hosts (6 -> 4) ==

  Missing    (2): shard-glk shard-glkb 


== Build changes ==

    * Linux: CI_DRM_4057 -> Patchwork_8697

  CI_DRM_4057: ac35105865ed2d4d9676fdb4752798b047fb126a @ git://anongit.freedesktop.org/gfx-ci/linux
  IGT_4432: 8b77704db49167f7ebfd1c470d9c129d3b862cb6 @ git://anongit.freedesktop.org/xorg/app/intel-gpu-tools
  Patchwork_8697: 5c78b9dc05bc38b3d767abc50a33b889e7cfd29d @ git://anongit.freedesktop.org/gfx-ci/linux
  piglit_4432: 93b35926a150e318439d2505901288594b3548f5 @ git://anongit.freedesktop.org/piglit

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_8697/shards.html
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state
  2018-04-16 15:53 [PATCH] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state Imre Deak
  2018-04-16 17:43 ` ✓ Fi.CI.BAT: success for " Patchwork
  2018-04-16 20:44 ` ✓ Fi.CI.IGT: " Patchwork
@ 2018-04-17  0:14 ` Clint Taylor
  2018-04-18 13:46   ` Jani Nikula
  2018-04-17 17:57 ` Ville Syrjälä
  3 siblings, 1 reply; 6+ messages in thread
From: Clint Taylor @ 2018-04-17  0:14 UTC (permalink / raw)
  To: Imre Deak, dri-devel, intel-gfx



On 04/16/2018 08:53 AM, Imre Deak wrote:
> LSPCON adapters in low-power state may ignore the first I2C write during
> TMDS output buffer enabling, resulting in a blank screen even with an
> otherwise enabled pipe. Fix this by reading back and validating the
> written value a few times.
>
> The problem was noticed on GLK machines with an onboard LSPCON adapter
> after entering/exiting DC5 power state. Doing an I2C read of the adapter
> ID as the first transaction - instead of the I2C write to enable the
> TMDS buffers - returns the correct value. Based on this we assume that
> the transaction itself is sent properly, it's only the adapter that is
> not ready for some reason to accept this first write after waking from
> low-power state. In my case the second I2C write attempt always
> succeeded.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105854
> Cc: Clinton Taylor <clinton.a.taylor@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>   drivers/gpu/drm/drm_dp_dual_mode_helper.c | 39 +++++++++++++++++++++++++------
>   1 file changed, 32 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> index 02a50929af67..e7f4fe2848a5 100644
> --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> @@ -350,19 +350,44 @@ int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type,
>   {
>   	uint8_t tmds_oen = enable ? 0 : DP_DUAL_MODE_TMDS_DISABLE;
>   	ssize_t ret;
> +	int retry;
>   
>   	if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
>   		return 0;
>   
> -	ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
> -				     &tmds_oen, sizeof(tmds_oen));
> -	if (ret) {
> -		DRM_DEBUG_KMS("Failed to %s TMDS output buffers\n",
> -			      enable ? "enable" : "disable");
> -		return ret;
> +	/*
> +	 * LSPCON adapters in low-power state may ignore the first write, so
> +	 * read back and verify the written value a few times.
> +	 */
> +	for (retry = 0; retry < 3; retry++) {
> +		uint8_t tmp;
> +
> +		ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
> +					     &tmds_oen, sizeof(tmds_oen));
> +		if (ret) {
> +			DRM_DEBUG_KMS("Failed to %s TMDS output buffers (%d attempts)\n",
> +				      enable ? "enable" : "disable",
> +				      retry + 1);
> +			return ret;
> +		}
> +
> +		ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
> +					    &tmp, sizeof(tmp));
> +		if (ret) {
> +			DRM_DEBUG_KMS("I2C read failed during TMDS output buffer %s (%d attempts)\n",
> +				      enable ? "enabling" : "disabling",
> +				      retry + 1);
> +			return ret;
> +		}
> +
> +		if (tmp == tmds_oen)
> +			return 0;
>   	}
>   
> -	return 0;
> +	DRM_DEBUG_KMS("I2C write value mismatch during TMDS output buffer %s\n",
> +		      enable ? "enabling" : "disabling");
> +
> +	return -EIO;
>   }
>   EXPORT_SYMBOL(drm_dp_dual_mode_set_tmds_output);
>   

Appears to fix the issue seen on GLK with LSPCON and DMC firmware 
loaded. Customer was concerned about the fix being in DRM instead of 
i915. However, there are no other SOCs that use this DRM function.

Reviewed-by: Clint Taylor <Clinton.A.Taylor@intel.com>
Tested-by: Clint Taylor <Clinton.A.Taylor@intel.com>

-Clint


_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state
  2018-04-16 15:53 [PATCH] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state Imre Deak
                   ` (2 preceding siblings ...)
  2018-04-17  0:14 ` [PATCH] " Clint Taylor
@ 2018-04-17 17:57 ` Ville Syrjälä
  3 siblings, 0 replies; 6+ messages in thread
From: Ville Syrjälä @ 2018-04-17 17:57 UTC (permalink / raw)
  To: Imre Deak; +Cc: intel-gfx, dri-devel

On Mon, Apr 16, 2018 at 06:53:09PM +0300, Imre Deak wrote:
> LSPCON adapters in low-power state may ignore the first I2C write during
> TMDS output buffer enabling, resulting in a blank screen even with an
> otherwise enabled pipe. Fix this by reading back and validating the
> written value a few times.
> 
> The problem was noticed on GLK machines with an onboard LSPCON adapter
> after entering/exiting DC5 power state. Doing an I2C read of the adapter
> ID as the first transaction - instead of the I2C write to enable the
> TMDS buffers - returns the correct value. Based on this we assume that
> the transaction itself is sent properly, it's only the adapter that is
> not ready for some reason to accept this first write after waking from
> low-power state. In my case the second I2C write attempt always
> succeeded.

Yeah, I guess this is an OK approach. Probably not much point in
optimizing the non-LSPCON case since this is modeset stuff,
although we do have the adaptor type passed in so we could if we
wanted to.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105854
> Cc: Clinton Taylor <clinton.a.taylor@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/drm_dp_dual_mode_helper.c | 39 +++++++++++++++++++++++++------
>  1 file changed, 32 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> index 02a50929af67..e7f4fe2848a5 100644
> --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> @@ -350,19 +350,44 @@ int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type,
>  {
>  	uint8_t tmds_oen = enable ? 0 : DP_DUAL_MODE_TMDS_DISABLE;
>  	ssize_t ret;
> +	int retry;
>  
>  	if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
>  		return 0;
>  
> -	ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
> -				     &tmds_oen, sizeof(tmds_oen));
> -	if (ret) {
> -		DRM_DEBUG_KMS("Failed to %s TMDS output buffers\n",
> -			      enable ? "enable" : "disable");
> -		return ret;
> +	/*
> +	 * LSPCON adapters in low-power state may ignore the first write, so
> +	 * read back and verify the written value a few times.
> +	 */
> +	for (retry = 0; retry < 3; retry++) {
> +		uint8_t tmp;
> +
> +		ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
> +					     &tmds_oen, sizeof(tmds_oen));
> +		if (ret) {
> +			DRM_DEBUG_KMS("Failed to %s TMDS output buffers (%d attempts)\n",
> +				      enable ? "enable" : "disable",
> +				      retry + 1);
> +			return ret;
> +		}
> +
> +		ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
> +					    &tmp, sizeof(tmp));
> +		if (ret) {
> +			DRM_DEBUG_KMS("I2C read failed during TMDS output buffer %s (%d attempts)\n",
> +				      enable ? "enabling" : "disabling",
> +				      retry + 1);
> +			return ret;
> +		}
> +
> +		if (tmp == tmds_oen)
> +			return 0;
>  	}
>  
> -	return 0;
> +	DRM_DEBUG_KMS("I2C write value mismatch during TMDS output buffer %s\n",
> +		      enable ? "enabling" : "disabling");
> +
> +	return -EIO;
>  }
>  EXPORT_SYMBOL(drm_dp_dual_mode_set_tmds_output);
>  
> -- 
> 2.13.2

-- 
Ville Syrjälä
Intel
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state
  2018-04-17  0:14 ` [PATCH] " Clint Taylor
@ 2018-04-18 13:46   ` Jani Nikula
  0 siblings, 0 replies; 6+ messages in thread
From: Jani Nikula @ 2018-04-18 13:46 UTC (permalink / raw)
  To: Clint Taylor, Imre Deak, dri-devel, intel-gfx

On Mon, 16 Apr 2018, Clint Taylor <clinton.a.taylor@intel.com> wrote:
> On 04/16/2018 08:53 AM, Imre Deak wrote:
>> LSPCON adapters in low-power state may ignore the first I2C write during
>> TMDS output buffer enabling, resulting in a blank screen even with an
>> otherwise enabled pipe. Fix this by reading back and validating the
>> written value a few times.
>>
>> The problem was noticed on GLK machines with an onboard LSPCON adapter
>> after entering/exiting DC5 power state. Doing an I2C read of the adapter
>> ID as the first transaction - instead of the I2C write to enable the
>> TMDS buffers - returns the correct value. Based on this we assume that
>> the transaction itself is sent properly, it's only the adapter that is
>> not ready for some reason to accept this first write after waking from
>> low-power state. In my case the second I2C write attempt always
>> succeeded.
>>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105854
>> Cc: Clinton Taylor <clinton.a.taylor@intel.com>
>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> Signed-off-by: Imre Deak <imre.deak@intel.com>
>> ---
>>   drivers/gpu/drm/drm_dp_dual_mode_helper.c | 39 +++++++++++++++++++++++++------
>>   1 file changed, 32 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>> index 02a50929af67..e7f4fe2848a5 100644
>> --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>> @@ -350,19 +350,44 @@ int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type,
>>   {
>>   	uint8_t tmds_oen = enable ? 0 : DP_DUAL_MODE_TMDS_DISABLE;
>>   	ssize_t ret;
>> +	int retry;
>>   
>>   	if (type < DRM_DP_DUAL_MODE_TYPE2_DVI)
>>   		return 0;
>>   
>> -	ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
>> -				     &tmds_oen, sizeof(tmds_oen));
>> -	if (ret) {
>> -		DRM_DEBUG_KMS("Failed to %s TMDS output buffers\n",
>> -			      enable ? "enable" : "disable");
>> -		return ret;
>> +	/*
>> +	 * LSPCON adapters in low-power state may ignore the first write, so
>> +	 * read back and verify the written value a few times.
>> +	 */
>> +	for (retry = 0; retry < 3; retry++) {
>> +		uint8_t tmp;
>> +
>> +		ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_TMDS_OEN,
>> +					     &tmds_oen, sizeof(tmds_oen));
>> +		if (ret) {
>> +			DRM_DEBUG_KMS("Failed to %s TMDS output buffers (%d attempts)\n",
>> +				      enable ? "enable" : "disable",
>> +				      retry + 1);
>> +			return ret;
>> +		}
>> +
>> +		ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_TMDS_OEN,
>> +					    &tmp, sizeof(tmp));
>> +		if (ret) {
>> +			DRM_DEBUG_KMS("I2C read failed during TMDS output buffer %s (%d attempts)\n",
>> +				      enable ? "enabling" : "disabling",
>> +				      retry + 1);
>> +			return ret;
>> +		}
>> +
>> +		if (tmp == tmds_oen)
>> +			return 0;
>>   	}
>>   
>> -	return 0;
>> +	DRM_DEBUG_KMS("I2C write value mismatch during TMDS output buffer %s\n",
>> +		      enable ? "enabling" : "disabling");
>> +
>> +	return -EIO;
>>   }
>>   EXPORT_SYMBOL(drm_dp_dual_mode_set_tmds_output);
>>   
>
> Appears to fix the issue seen on GLK with LSPCON and DMC firmware 
> loaded. Customer was concerned about the fix being in DRM instead of 
> i915. However, there are no other SOCs that use this DRM function.
>
> Reviewed-by: Clint Taylor <Clinton.A.Taylor@intel.com>
> Tested-by: Clint Taylor <Clinton.A.Taylor@intel.com>

Pushed to drm-misc-fixes, thanks for the patch.

Clint and Ville, many thanks for your testing and review, alas I screwed
up and pushed this without the tags added to the commit. I'm sorry. I
expect better from myself. :(

BR,
Jani.


>
> -Clint
>
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Jani Nikula, Intel Open Source Technology Center
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2018-04-18 13:46 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-04-16 15:53 [PATCH] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state Imre Deak
2018-04-16 17:43 ` ✓ Fi.CI.BAT: success for " Patchwork
2018-04-16 20:44 ` ✓ Fi.CI.IGT: " Patchwork
2018-04-17  0:14 ` [PATCH] " Clint Taylor
2018-04-18 13:46   ` Jani Nikula
2018-04-17 17:57 ` Ville Syrjälä

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.