[PATCH] drm/amd/display: Use freesync when `DRM_EDID_FEATURE_CONTINUOUS_FREQ` found

[Harry Wentland]

On 2024-03-05 15:57, Mario Limonciello wrote:
> The monitor shipped with the Framework 16 supports VRR [1], but it's not
> being advertised.
> 
> This is because the detailed timing block doesn't contain
> `EDID_DETAIL_MONITOR_RANGE` which amdgpu looks for to find min and max
> frequencies.  This check however is superfluous for this case because
> update_display_info() calls drm_get_monitor_range() to get these ranges
> already.
> 
> So if the `DRM_EDID_FEATURE_CONTINUOUS_FREQ` EDID feature is found then
> turn on freesync without extra checks.
> 
> Closes: https://www.reddit.com/r/framework/comments/1b4y2i5/no_variable_refresh_rate_on_the_framework_16_on/
> Closes: https://www.reddit.com/r/framework/comments/1b6vzcy/framework_16_variable_refresh_rate/
> Closes: https://community.frame.work/t/resolved-no-vrr-freesync-with-amd-version/42338
> Link: https://gist.github.com/superm1/e8fbacfa4d0f53150231d3a3e0a13faf [1]
> Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 5b7293da5453..38186d669a85 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -11238,9 +11238,12 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
>   		bool edid_check_required = false;
>   
>   		if (edid) {
> -			edid_check_required = is_dp_capable_without_timing_msa(
> -						adev->dm.dc,
> -						amdgpu_dm_connector);
> +			if (edid->features & DRM_EDID_FEATURE_CONTINUOUS_FREQ)
> +				freesync_capable = true;

We still need to check that the DP RX is capable of being
driven without MSA, i.e., we should do

freesync_capable = is_dp_capable_without_timing_msa(...)

Harry

> +			else
> +				edid_check_required = is_dp_capable_without_timing_msa(
> +							adev->dm.dc,
> +							amdgpu_dm_connector);
>   		}
>   
>   		if (edid_check_required == true && (edid->version > 1 ||