[Intel-gfx] [PATCH 1/2] drm/i915: Do not enable FEC without DSC

[Ville Syrjälä]

On Thu, Apr 11, 2019 at 12:11:42PM -0700, Manasi Navare wrote:
> On Tue, Mar 26, 2019 at 04:49:02PM +0200, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > Currently we enable FEC even when DSC is no used. While that is
> > theoretically valid supposedly there isn't much of a benefit from
> > this. But more importantly we do not account for the FEC link
> > bandwidth overhead (2.4%) in the non-DSC link bandwidth computations.
> > So the code may think we have enough bandwidth when we in fact
> > do not.
> > 
> > Cc: Anusha Srivatsa <anusha.srivatsa at intel.com>
> > Cc: Manasi Navare <manasi.d.navare at intel.comk>
> 
> There is a typo in the email address:
> manasi.d.navare at intel.com

Thanks for the reminder. I already forgot about this and was about to
push without fixing it. Sadly it seems I had copy pasted it from the
same place to both of these patches, so one got pushed with the bad
address.

Hmm. Looks like this escaped into 5.0 already. Added cc:stable
and pushed to dinq. Thanks for the review.

> 
> > Fixes: 240999cf339f ("i915/dp/fec: Add fec_enable to the crtc state.")
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Makes sense to me
> 
> Reviewed-by: Manasi Navare <manasi.d.navare at intel.com>
> 
> Manasi
> 
> > ---
> >  drivers/gpu/drm/i915/intel_dp.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 326de12c3f44..bbf678561509 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -1925,6 +1925,9 @@ static int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
> >  	int pipe_bpp;
> >  	int ret;
> >  
> > +	pipe_config->fec_enable = !intel_dp_is_edp(intel_dp) &&
> > +		intel_dp_supports_fec(intel_dp, pipe_config);
> > +
> >  	if (!intel_dp_supports_dsc(intel_dp, pipe_config))
> >  		return -EINVAL;
> >  
> > @@ -2168,9 +2171,6 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> >  	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
> >  		return -EINVAL;
> >  
> > -	pipe_config->fec_enable = !intel_dp_is_edp(intel_dp) &&
> > -				  intel_dp_supports_fec(intel_dp, pipe_config);
> > -
> >  	ret = intel_dp_compute_link_config(encoder, pipe_config, conn_state);
> >  	if (ret < 0)
> >  		return ret;
> > -- 
> > 2.19.2
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel