ACK/Cmnt: [OEM-5.14/Jammy][PATCH 1/1] UBUNTU: SAUCE: Revert "drm/i915/display: Remove check for low voltage sku for max dp source rate"

[Stefan Bader]

On 04.07.22 07:15, Aaron Ma wrote:
> BugLink: https://bugs.launchpad.net/bugs/1980621
> 
> This reverts commit ed3fc6452562128cdd3c6f9ce8dc24ca4651d1cf.
> 
> This commit was claimed to backport
> commit 73867c8709b5 ("drm/i915/display: Remove check for low voltage sku for max dp source rate")
> that is reverted by upstream:
> commit c7b28f52f406 ("drm/i915/display: Re-add check for low voltage sku for max dp source rate")
> 
> But it's not. So revert it instead of upstream commit.
> It causes blanck screen on ThinkPad ADL platform.
> 
> Signed-off-by: Aaron Ma <aaron.ma at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---

The SHA1 of the revert for Jammy is 69991d3b4a1fe18f9567725f348a3aa8ea44e3f3 
which can be fixed when applying. Without the long background story it is hard 
to know how low voltage check relates to some rate limits. Especially when the 
cherry pick is in fact a backport. And maybe should have been a SAUCE with a lot 
of explanation so there is a chance to realize what was going on.

-Stefan

>   drivers/gpu/drm/i915/display/intel_dp.c | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 45ce9846ab973..631cf7d4323c8 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -283,10 +283,7 @@ intel_dp_set_source_rates(struct intel_dp *intel_dp)
>   	if (DISPLAY_VER(dev_priv) >= 11) {
>   		source_rates = icl_rates;
>   		size = ARRAY_SIZE(icl_rates);
> -		if (IS_ALDERLAKE_P(dev_priv) || IS_ALDERLAKE_S(dev_priv) ||
> -			 IS_DG1(dev_priv) || IS_ROCKETLAKE(dev_priv))
> -			max_rate = 810000;
> -		else if (IS_JSL_EHL(dev_priv))
> +		if (IS_JSL_EHL(dev_priv))
>   			max_rate = ehl_max_source_rate(intel_dp);
>   		else
>   			max_rate = icl_max_source_rate(intel_dp);

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