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.mur...@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-v2-1-9110a9342...@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-v1-1-5c100e4a8...@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.mur...@intel.com>
>
