Re: [PATCH v4 07/27] drm/amd/display: Use bigger VRR range if found in AMD vsdb

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 16 Feb 2026, Tomasz Pakuła <tomasz.pakula.oficjalny@gmail.com> wrote:
> [Why]
> Some monitors only expose their full VRR range in AMD vsdb for some
> reason.
>
> [How]
> Compare exposed ranges and use the bigger one.
> Only adjust lower limit if it doesn't support LFC
>
> Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4177
> Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@gmail.com>
> ---
>  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 31 +++++++++++++++++++
>  1 file changed, 31 insertions(+)
>
> 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 b3bf5e0c19a5..f36059bb0324 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -13269,6 +13269,34 @@ static bool copy_range_to_amdgpu_connector(struct drm_connector *conn)
>  	return is_freesync_capable(range);
>  }
>  
> +static void extend_range_from_vsdb(struct drm_display_info *display,
> +				   const struct amdgpu_hdmi_vsdb_info *vsdb)
> +{
> +	u16 vrr_min = display->monitor_range.min_vfreq;
> +	u16 vrr_max = display->monitor_range.max_vfreq;
> +
> +	/* Always extend upper limit */
> +	if (vsdb->max_refresh_rate_hz > vrr_max)
> +		vrr_max = vsdb->max_refresh_rate_hz;
> +
> +	/*
> +	 * Only extend lower limit if current one disables LFC.
> +
> +	 * During widespread testing, we found that some manufacturers probably
> +	 * had issues with their monitors' lower VRR boundaries and adjusted
> +	 * them up (Gigabyte X34GS with official range 48 - 180, AMD vsdb 48 -
> +	 * 180 yet Monitor Ranges 55 - 180). After setting the lower boundary
> +	 * from AMD vsdb, such monitors start having blanking issues.
> +	 *
> +	 * Work around that by not touching VRR min if it still supports LFC.
> +	 */
> +	if (vsdb->min_refresh_rate_hz < vrr_min && (vrr_min * 2 >= vrr_max))
> +		vrr_min = vsdb->min_refresh_rate_hz;
> +
> +	display->monitor_range.min_vfreq = vrr_min;
> +	display->monitor_range.max_vfreq = vrr_max;

Random driver code should *not* modify struct drm_display_info,
especially the fields that drm_edid.c parses. Drivers should cease to
parse EDID and DisplayID altogether.

I'm on the verge of NAKing, to the extent that I have control over this,
any further improvements on driver EDID/DisplayID parsing, with the
expectation that everything's moved to shared EDID parser in drm_edid.c
first, and improved there.

BR,
Jani.


> +}
> +
>  /**
>   * amdgpu_dm_update_freesync_caps - Update Freesync capabilities
>   *
> @@ -13339,6 +13367,9 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
>  		if (is_monitor_range_invalid(connector))
>  			monitor_range_from_vsdb(&connector->display_info, &vsdb_info);
>  
> +		/* Try extending range if found in AMD vsdb */
> +		extend_range_from_vsdb(&connector->display_info, &vsdb_info);
> +
>  		if (dpcd_caps.allow_invalid_MSA_timing_param)
>  			freesync_capable = copy_range_to_amdgpu_connector(connector);

-- 
Jani Nikula, Intel