[PATCH v2] drm/i915/dsc: Change rc parameters calculation for DSC 1.1

[Tseng, William]

> -----Original Message-----
> From: Kandpal, Suraj <suraj.kandpal at intel.com>
> Sent: Friday, February 21, 2025 11:43 AM
> To: Tseng, William <william.tseng at intel.com>; intel-gfx at lists.freedesktop.org
> Cc: Heikkila, Juha-pekka <juha-pekka.heikkila at intel.com>
> Subject: RE: [PATCH v2] drm/i915/dsc: Change rc parameters calculation for
> DSC 1.1
> 
> 
> 
> > -----Original Message-----
> > From: Tseng, William <william.tseng at intel.com>
> > Sent: Friday, February 21, 2025 7:27 AM
> > To: intel-gfx at lists.freedesktop.org
> > Cc: Tseng, William <william.tseng at intel.com>; Kandpal, Suraj
> > <suraj.kandpal at intel.com>; Heikkila, Juha-pekka <juha-
> > pekka.heikkila at intel.com>
> > Subject: [PATCH v2] drm/i915/dsc: Change rc parameters calculation for
> > DSC 1.1
> 
> I think you missed one of my previous comments in which I asked you to send
> it to the intel-xe mailing list So that the CI can test more thoroughly.
> Also this patch is causing a regression on DG2 + DSC 1.1 config my guess is it
> would cause a issue on any Machine 13 and above with DSC 1.1 when input
> bpp is 24 and compressed bpp is 18
> 

Sorry for missing the comment about the mailing list intel-xe.
I will send the revised patch to it next time.

As to the regression concern, I think it won't happen if DSC 1.1
does not support the case of input bpp is 24 and compressed bpp is 18.
What do you think of it?

> >
> > When calculating dsc parameters, the rc parameters calculated by
> > calculate_rc_params() is incorrect in the case of DSC 1.1 and
> > DISPLAY_VER(dev_priv) >= 13. It turns out to be some noise-like lines
> > are displayed on a MIPI DSI panel supporting DSC 1.1.
> >
> > The function calculate_rc_params() is implemented by following the
> > Table E-2 in DSC 1.2a and creates incorrect rc parameters for DSC 1.1.
> > As a result, add the additional condition (vdsc_cfg->dsc_version_minor
> > >= 2) to get the right function to calculate rc parameters for DSC 1.1.
> >
> > v1: initial version.
> > v2: modify the commit comment and change the condition
> >     regarding DSC version checking.
> >
> > Cc: Suraj Kandpal <suraj.kandpal at intel.com>
> > Cc: Juha-Pekka Heikkil <juha-pekka.heikkila at intel.com>
> > Signed-off-by: William Tseng <william.tseng at intel.com>
> 
> Needs a closes-by tag
> 

Will add closes-by as the line. Is it correct?
closes-by : https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13719

Regards
William

> Regards,
> Suraj Kandpal
> 
> > ---
> >  drivers/gpu/drm/i915/display/intel_vdsc.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c
> > b/drivers/gpu/drm/i915/display/intel_vdsc.c
> > index b355c479eda3..b0a7a2179844 100644
> > --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
> > @@ -320,7 +320,7 @@ int intel_dsc_compute_params(struct
> > intel_crtc_state
> > *pipe_config)
> >  	 * upto uncompressed bpp-1, hence add calculations for all the rc
> >  	 * parameters
> >  	 */
> > -	if (DISPLAY_VER(dev_priv) >= 13) {
> > +	if (DISPLAY_VER(dev_priv) >= 13 && vdsc_cfg->dsc_version_minor >=
> > 2) {
> >  		calculate_rc_params(vdsc_cfg);
> >  	} else {
> >  		if ((compressed_bpp == 8 ||
> > --
> > 2.34.1