Re: [Intel-gfx] [PATCH 05/19] drm/i915/dp: Update Bigjoiner interface bits for computing compressed bpp

["Lisovskiy, Stanislav" <stanislav.lisovskiy@intel.com>]

On Mon, Jul 24, 2023 at 05:49:11PM +0530, Nautiyal, Ankit K wrote:
> Hi Stan,
> 
> Thanks for the reviews ans suggestions. Please my response inline:
> 
> 
> On 7/20/2023 2:59 PM, Lisovskiy, Stanislav wrote:
> > On Thu, Jul 13, 2023 at 04:03:32PM +0530, Ankit Nautiyal wrote:
> > > In Bigjoiner check for DSC, bigjoiner interface bits for DP for
> > > DISPLAY > 13 is 36 (Bspec: 49259).
> > > 
> > > v2: Corrected Display ver to 13.
> > > 
> > > v3: Follow convention for conditional statement. (Ville)
> > > 
> > > v4: Fix check for display ver. (Ville)
> > > 
> > > Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> > > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > ---
> > >   drivers/gpu/drm/i915/display/intel_dp.c | 3 ++-
> > >   1 file changed, 2 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > > index 19768ac658ba..c1fd448d80e1 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > > @@ -802,8 +802,9 @@ u16 intel_dp_dsc_get_max_compressed_bpp(struct drm_i915_private *i915,
> > >   	bits_per_pixel = min(bits_per_pixel, max_bpp_small_joiner_ram);
> > >   	if (bigjoiner) {
> > > +		int bigjoiner_interface_bits = DISPLAY_VER(i915) >= 14 ? 36 : 24;
> > >   		u32 max_bpp_bigjoiner =
> > > -			i915->display.cdclk.max_cdclk_freq * 48 /
> > > +			i915->display.cdclk.max_cdclk_freq * 2 * bigjoiner_interface_bits /
> > Probably "num_vdsc_instances = intel_dsc_get_num_vdsc_instances(crtc_state);" again,
> > instead of "2"?
> 
> Currently intel_dsc_get_num_vdsc_instances will give total number of
> vdsc_engines including joined pipes.
> 
> So with bigjoiner the function will return 4.
> 
> This was good to calculate Pipe BW check: (Pixel clock < PPC * CDCLK
> frequency * Number of pipes joined
> 
> as we get PPC * number of pipes joined from
> intel_dsc_get_num_vdsc_instances)
> 
> Or to calculate DSC_PIC_WIDTH PPS parameter.
> 
> But here we perhaps need intel_dsc_get_vdsc_engines_per_pipe that will just
> return 2 if dsc_split 1 otherwise.
> 
> Thanks & Regards,
> 
> Ankit

Yes, I agree, unfortunately not applicable here.
May be yeah we need some function like that and then refactor
also the intel_dsc_get_num_vdsc_instances to use that one..

Stan

> 
> > 
> > With that clarified,
> > 
> > Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > 
> > >   			intel_dp_mode_to_fec_clock(mode_clock);
> > >   		bits_per_pixel = min(bits_per_pixel, max_bpp_bigjoiner);
> > > -- 
> > > 2.40.1
> > >