[Intel-gfx] [PATCH 02/23] HAX drm/i915: Disable FEC entirely for now

[Maarten Lankhorst]

Op 20-09-2019 om 13:42 schreef Maarten Lankhorst:
> I get a permanent FIFO underrun when enabling FEC with big joiner,
> so for now disable it.
>
> It seems that even at 1024x768 resolution without bigjoiner we don't
> get a working configuration. Flag is set but vblank timing shows that
> vblanks are delivered slightly faster, so the extra overhead we
> calculated for data M/N goes unused.
>
> Not-Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 4dfb78dc7fa2..02242a16640b 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1877,7 +1877,8 @@ static bool intel_dp_source_supports_dsc(struct intel_dp *intel_dp,
>  static bool intel_dp_supports_dsc(struct intel_dp *intel_dp,
>  				  const struct intel_crtc_state *pipe_config)
>  {
> -	if (!intel_dp_is_edp(intel_dp) && !pipe_config->fec_enable)
> +	/* HACK: Disable FEC until we solved FIFO underruns */
> +	if (!intel_dp_is_edp(intel_dp) && !pipe_config->fec_enable && 0)
>  		return false;
>  
>  	return intel_dp_source_supports_dsc(intel_dp, pipe_config) &&
> @@ -2024,8 +2025,9 @@ static int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
>  	int pipe_bpp;
>  	int ret;
>  
> +	/* HACK: Disable FEC until we solved FIFO underruns */
>  	pipe_config->fec_enable = !intel_dp_is_edp(intel_dp) &&
> -		intel_dp_supports_fec(intel_dp, pipe_config);
> +		intel_dp_supports_fec(intel_dp, pipe_config) && 0;
>  
>  	if (!intel_dp_supports_dsc(intel_dp, pipe_config))
>  		return -EINVAL;

With v3 of the previous patch, this is now obsolete and confirmed working on ICL.

So this can finally be dropped. :)