[PATCH v3] drm/i915/display: Use the recomended min_hblank values

[PATCH v3] drm/i915/display: Use the recomended min_hblank values

[Arun R Murthy]

Use recommended values as per wa_14021694213 to compare with the
calculated value and choose minimum of them.

v2: corrected checkpatch warning and retain the restriction for
min_hblank (Jani)
v3: use calculated value to compare with recomended value and choose
minimum of them (Imre)

Bspec: 74379
Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
---
Changes in v3:
- EDITME: describe what is new in this series revision.
- EDITME: use bulletpoints and terse descriptions.
- Link to v2: https://lore.kernel.org/r/20250624-min_hblank-v2-1-9110a9342d8c@intel.com

Changes in v2:
- EDITME: describe what is new in this series revision.
- EDITME: use bulletpoints and terse descriptions.
- Link to v1: https://lore.kernel.org/r/20250624-min_hblank-v1-1-5c100e4a8b05@intel.com
---
 drivers/gpu/drm/i915/display/intel_dp.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index f48912f308df7fd26c9d089e8f1bd096bfc8df95..c55315fb74734fded40695bae40dd19f71a9786f 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3175,7 +3175,22 @@ int intel_dp_compute_min_hblank(struct intel_crtc_state *crtc_state,
 	 */
 	min_hblank = min_hblank - 2;
 
-	min_hblank = min(10, min_hblank);
+	/*
+	 * min_hblank formula is undergoing a change, to avoid underrun use the
+	 * recomended value in spec to compare with the calculated one and use the
+	 * minimum value
+	 */
+	if (intel_dp_is_uhbr(crtc_state)) {
+		if (crtc_state->dsc.compression_enable &&
+		    crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 &&
+		    crtc_state->pipe_bpp == 18)
+			min_hblank = min(2, min_hblank);
+		else
+			min_hblank = min(3, min_hblank);
+	} else {
+		min_hblank = min(10, min_hblank);
+	}
+
 	crtc_state->min_hblank = min_hblank;
 
 	return 0;

---
base-commit: da56936fad6f5e1d5f0cef8b50277bfb071eefe7
change-id: 20250624-min_hblank-8af8d2626ff8

Best regards,
-- 
Arun R Murthy <arun.r.murthy@intel.com>

✗ i915.CI.BAT: failure for drm/i915/display: Use the recomended min_hblank values

[Patchwork]

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== Series Details ==

Series: drm/i915/display: Use the recomended min_hblank values
URL   : https://patchwork.freedesktop.org/series/150726/
State : failure

== Summary ==

CI Bug Log - changes from CI_DRM_16753 -> Patchwork_150726v1
====================================================

Summary
-------

  **FAILURE**

  Serious unknown changes coming with Patchwork_150726v1 absolutely need to be
  verified manually.
  
  If you think the reported changes have nothing to do with the changes
  introduced in Patchwork_150726v1, please notify your bug team (I915-ci-infra@lists.freedesktop.org) to allow them
  to document this new failure mode, which will reduce false positives in CI.

  External URL: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/index.html

Participating hosts (44 -> 42)
------------------------------

  Missing    (2): fi-glk-j4005 fi-snb-2520m 

Possible new issues
-------------------

  Here are the unknown changes that may have been introduced in Patchwork_150726v1:

### IGT changes ###

#### Possible regressions ####

  * igt@i915_selftest@live@guc_hang:
    - bat-arlh-2:         [PASS][1] -> [INCOMPLETE][2]
   [1]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/bat-arlh-2/igt@i915_selftest@live@guc_hang.html
   [2]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-arlh-2/igt@i915_selftest@live@guc_hang.html

  
Known issues
------------

  Here are the changes found in Patchwork_150726v1 that come from known issues:

### IGT changes ###

#### Issues hit ####

  * igt@i915_selftest@live:
    - bat-mtlp-8:         [PASS][3] -> [DMESG-FAIL][4] ([i915#12061]) +1 other test dmesg-fail
   [3]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/bat-mtlp-8/igt@i915_selftest@live.html
   [4]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-mtlp-8/igt@i915_selftest@live.html
    - bat-arlh-2:         [PASS][5] -> [INCOMPLETE][6] ([i915#14046] / [i915#14393])
   [5]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/bat-arlh-2/igt@i915_selftest@live.html
   [6]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-arlh-2/igt@i915_selftest@live.html

  * igt@i915_selftest@live@active:
    - bat-dg2-14:         NOTRUN -> [INCOMPLETE][7] ([i915#14201])
   [7]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-dg2-14/igt@i915_selftest@live@active.html

  * igt@i915_selftest@live@workarounds:
    - bat-dg2-9:          NOTRUN -> [DMESG-FAIL][8] ([i915#12061]) +1 other test dmesg-fail
   [8]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-dg2-9/igt@i915_selftest@live@workarounds.html
    - bat-dg2-11:         [PASS][9] -> [DMESG-FAIL][10] ([i915#12061]) +1 other test dmesg-fail
   [9]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/bat-dg2-11/igt@i915_selftest@live@workarounds.html
   [10]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-dg2-11/igt@i915_selftest@live@workarounds.html

  
#### Possible fixes ####

  * igt@dmabuf@all-tests@dma_fence_chain:
    - fi-bsw-nick:        [INCOMPLETE][11] ([i915#12904]) -> [PASS][12] +1 other test pass
   [11]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/fi-bsw-nick/igt@dmabuf@all-tests@dma_fence_chain.html
   [12]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/fi-bsw-nick/igt@dmabuf@all-tests@dma_fence_chain.html

  * igt@fbdev@info:
    - fi-ivb-3770:        [SKIP][13] ([i915#1849]) -> [PASS][14]
   [13]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/fi-ivb-3770/igt@fbdev@info.html
   [14]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/fi-ivb-3770/igt@fbdev@info.html

  * igt@fbdev@read:
    - fi-ivb-3770:        [SKIP][15] -> [PASS][16] +3 other tests pass
   [15]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/fi-ivb-3770/igt@fbdev@read.html
   [16]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/fi-ivb-3770/igt@fbdev@read.html

  * igt@i915_pm_rpm@module-reload:
    - bat-dg2-9:          [ABORT][17] ([i915#14385]) -> [PASS][18]
   [17]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/bat-dg2-9/igt@i915_pm_rpm@module-reload.html
   [18]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-dg2-9/igt@i915_pm_rpm@module-reload.html

  * igt@i915_selftest@live:
    - bat-arlh-3:         [INCOMPLETE][19] ([i915#14393]) -> [PASS][20] +1 other test pass
   [19]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/bat-arlh-3/igt@i915_selftest@live.html
   [20]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-arlh-3/igt@i915_selftest@live.html

  * igt@i915_selftest@live@sanitycheck:
    - bat-dg2-14:         [ABORT][21] ([i915#14201]) -> [PASS][22]
   [21]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/bat-dg2-14/igt@i915_selftest@live@sanitycheck.html
   [22]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-dg2-14/igt@i915_selftest@live@sanitycheck.html

  
#### Warnings ####

  * igt@i915_selftest@live:
    - bat-dg2-14:         [ABORT][23] ([i915#14201]) -> [INCOMPLETE][24] ([i915#14201] / [i915#14393])
   [23]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/bat-dg2-14/igt@i915_selftest@live.html
   [24]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-dg2-14/igt@i915_selftest@live.html
    - bat-atsm-1:         [DMESG-FAIL][25] ([i915#12061] / [i915#13929]) -> [DMESG-FAIL][26] ([i915#12061] / [i915#14204])
   [25]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/bat-atsm-1/igt@i915_selftest@live.html
   [26]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-atsm-1/igt@i915_selftest@live.html

  * igt@i915_selftest@live@mman:
    - bat-atsm-1:         [DMESG-FAIL][27] ([i915#13929]) -> [DMESG-FAIL][28] ([i915#14204])
   [27]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16753/bat-atsm-1/igt@i915_selftest@live@mman.html
   [28]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/bat-atsm-1/igt@i915_selftest@live@mman.html

  
  [i915#12061]: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/12061
  [i915#12904]: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/12904
  [i915#13929]: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13929
  [i915#14046]: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14046
  [i915#14201]: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14201
  [i915#14204]: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14204
  [i915#14385]: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14385
  [i915#14393]: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14393
  [i915#1849]: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/1849


Build changes
-------------

  * Linux: CI_DRM_16753 -> Patchwork_150726v1

  CI-20190529: 20190529
  CI_DRM_16753: bd57aee20daefb7b0dfe9017663668c92115ff19 @ git://anongit.freedesktop.org/gfx-ci/linux
  IGT_8424: 68588b3c89a1bbe08c54d21c4d3d2e509957c795 @ https://gitlab.freedesktop.org/drm/igt-gpu-tools.git
  Patchwork_150726v1: bd57aee20daefb7b0dfe9017663668c92115ff19 @ git://anongit.freedesktop.org/gfx-ci/linux

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_150726v1/index.html

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Re: [PATCH v3] drm/i915/display: Use the recomended min_hblank values

[Imre Deak]

On Wed, Jun 25, 2025 at 11:04:07AM +0530, Arun R Murthy wrote:
> Use recommended values as per wa_14021694213 to compare with the
> calculated value and choose minimum of them.
> 
> v2: corrected checkpatch warning and retain the restriction for
> min_hblank (Jani)
> v3: use calculated value to compare with recomended value and choose
> minimum of them (Imre)
> 
> Bspec: 74379
> Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
> ---
> Changes in v3:
> - EDITME: describe what is new in this series revision.
> - EDITME: use bulletpoints and terse descriptions.
> - Link to v2: https://lore.kernel.org/r/20250624-min_hblank-v2-1-9110a9342d8c@intel.com
> 
> Changes in v2:
> - EDITME: describe what is new in this series revision.
> - EDITME: use bulletpoints and terse descriptions.
> - Link to v1: https://lore.kernel.org/r/20250624-min_hblank-v1-1-5c100e4a8b05@intel.com

The above 'Changes in vx' templates could be removed imo.

> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index f48912f308df7fd26c9d089e8f1bd096bfc8df95..c55315fb74734fded40695bae40dd19f71a9786f 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3175,7 +3175,22 @@ int intel_dp_compute_min_hblank(struct intel_crtc_state *crtc_state,
>  	 */
>  	min_hblank = min_hblank - 2;
>  
> -	min_hblank = min(10, min_hblank);
> +	/*
> +	 * min_hblank formula is undergoing a change, to avoid underrun use the
> +	 * recomended value in spec to compare with the calculated one and use the
> +	 * minimum value
> +	 */
> +	if (intel_dp_is_uhbr(crtc_state)) {
> +		if (crtc_state->dsc.compression_enable &&
> +		    crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 &&
> +		    crtc_state->pipe_bpp == 18)

The bspec page describes this format as YUV420 at 6 bpp. Not sure how
that would align with pipe_bpp == 18 (which is 6 _bpc_). Bspec could
also refer to the compressed bpp, however the driver's minimum
compressed bpp is 8. Could you clarify which bpp bspec refers to?

> +			min_hblank = min(2, min_hblank);
> +		else
> +			min_hblank = min(3, min_hblank);
> +	} else {
> +		min_hblank = min(10, min_hblank);
> +	}
> +
>  	crtc_state->min_hblank = min_hblank;
>  
>  	return 0;
> 
> ---
> base-commit: da56936fad6f5e1d5f0cef8b50277bfb071eefe7
> change-id: 20250624-min_hblank-8af8d2626ff8
> 
> Best regards,
> -- 
> Arun R Murthy <arun.r.murthy@intel.com>
> 

Re: [PATCH v3] drm/i915/display: Use the recomended min_hblank values

[Murthy, Arun R]

On 25-06-2025 22:59, Imre Deak wrote:
> On Wed, Jun 25, 2025 at 11:04:07AM +0530, Arun R Murthy wrote:
>> Use recommended values as per wa_14021694213 to compare with the
>> calculated value and choose minimum of them.
>>
>> v2: corrected checkpatch warning and retain the restriction for
>> min_hblank (Jani)
>> v3: use calculated value to compare with recomended value and choose
>> minimum of them (Imre)
>>
>> Bspec: 74379
>> Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
>> ---
>> Changes in v3:
>> - EDITME: describe what is new in this series revision.
>> - EDITME: use bulletpoints and terse descriptions.
>> - Link to v2: https://lore.kernel.org/r/20250624-min_hblank-v2-1-9110a9342d8c@intel.com
>>
>> Changes in v2:
>> - EDITME: describe what is new in this series revision.
>> - EDITME: use bulletpoints and terse descriptions.
>> - Link to v1: https://lore.kernel.org/r/20250624-min_hblank-v1-1-5c100e4a8b05@intel.com
> The above 'Changes in vx' templates could be removed imo.
>
>> ---
>>   drivers/gpu/drm/i915/display/intel_dp.c | 17 ++++++++++++++++-
>>   1 file changed, 16 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
>> index f48912f308df7fd26c9d089e8f1bd096bfc8df95..c55315fb74734fded40695bae40dd19f71a9786f 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>> @@ -3175,7 +3175,22 @@ int intel_dp_compute_min_hblank(struct intel_crtc_state *crtc_state,
>>   	 */
>>   	min_hblank = min_hblank - 2;
>>   
>> -	min_hblank = min(10, min_hblank);
>> +	/*
>> +	 * min_hblank formula is undergoing a change, to avoid underrun use the
>> +	 * recomended value in spec to compare with the calculated one and use the
>> +	 * minimum value
>> +	 */
>> +	if (intel_dp_is_uhbr(crtc_state)) {
>> +		if (crtc_state->dsc.compression_enable &&
>> +		    crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 &&
>> +		    crtc_state->pipe_bpp == 18)
> The bspec page describes this format as YUV420 at 6 bpp. Not sure how
> that would align with pipe_bpp == 18 (which is 6 _bpc_). Bspec could
> also refer to the compressed bpp, however the driver's minimum
> compressed bpp is 8. Could you clarify which bpp bspec refers to?

Here since the check if for DSC, its compressed bpp and even though 
driver's minimum bpc is 8 as per the calculations for bpc 6 min_hblank 
should be 2.

Thanks and Regards,
Arun R Murthy
-------------------

>
>> +			min_hblank = min(2, min_hblank);
>> +		else
>> +			min_hblank = min(3, min_hblank);
>> +	} else {
>> +		min_hblank = min(10, min_hblank);
>> +	}
>> +
>>   	crtc_state->min_hblank = min_hblank;
>>   
>>   	return 0;
>>
>> ---
>> base-commit: da56936fad6f5e1d5f0cef8b50277bfb071eefe7
>> change-id: 20250624-min_hblank-8af8d2626ff8
>>
>> Best regards,
>> -- 
>> Arun R Murthy <arun.r.murthy@intel.com>
>>