[Intel-gfx] [PATCH 3/5] drm/i915: Check for unsupported DP link rates during initial commit

[Ville Syrjälä]

On Sat, Oct 03, 2020 at 03:18:44AM +0300, Imre Deak wrote:
> Some BIOSes set an unsupported/imprecise DP link rate (for instance on
> TGL A stepping). Make sure that we do an encoder recompute and a modeset
> in this case.
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak at intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index d33a3d9fdc3a..df5277c2b9ba 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3707,6 +3707,18 @@ bool intel_dp_initial_fastset_check(struct intel_encoder *encoder,
>  				    struct intel_crtc_state *crtc_state)
>  {
>  	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
> +	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> +
> +	/*
> +	 * If BIOS has set an unsupported or non-standard link rate for some
> +	 * reason force an encoder recompute and full modeset.
> +	 */
> +	if (intel_dp_rate_index(intel_dp->source_rates, intel_dp->num_source_rates,
> +				crtc_state->port_clock) < 0) {
> +		drm_dbg_kms(&i915->drm, "Forcing full modeset due to unsupported link rate\n");
> +		crtc_state->uapi.connectors_changed = true;
> +		return false;
> +	}
>  
>  	/*
>  	 * FIXME hack to force full modeset when DSC is being used.
> -- 
> 2.25.1

-- 
Ville Syrjälä
Intel