[PATCH] drm/i915/icl: Update csc and gamma enable checks

[Matt Roper]

On Thu, Oct 03, 2024 at 06:46:31PM +0300, Ville Syrjälä wrote:
> On Thu, Oct 03, 2024 at 09:08:53PM +0530, Pottumuttu, Sai Teja wrote:
> > 
> > On 03-10-2024 20:28, Ville Syrjälä wrote:
> > > On Thu, Oct 03, 2024 at 05:32:56PM +0300, Ville Syrjälä wrote:
> > >> On Thu, Oct 03, 2024 at 07:22:37AM -0700, Matt Roper wrote:
> > >>> On Thu, Oct 03, 2024 at 02:10:31PM +0300, Ville Syrjälä wrote:
> > >>>> On Thu, Oct 03, 2024 at 02:33:41PM +0530, Sai Teja Pottumuttu wrote:
> > >>>>> With ICL, we have a way to check if gamma and csc are enabled on
> > >>>>> a pipe using bits in GAMMA_MODE and CSC_MODE. So, use them as well
> > >>>>> along with the existing BOTTOM_COLOR checks.
> > >>>>>
> > >>>>> BSpec: 7463, 7466
> > >>>>> Signed-off-by: Sai Teja Pottumuttu <sai.teja.pottumuttu at intel.com>
> > >>>>> ---
> > >>>>>   drivers/gpu/drm/i915/display/intel_color.c | 24 ++++++++++++++++++++--
> > >>>>>   1 file changed, 22 insertions(+), 2 deletions(-)
> > >>>>>
> > >>>>> diff --git a/drivers/gpu/drm/i915/display/intel_color.c b/drivers/gpu/drm/i915/display/intel_color.c
> > >>>>> index 50f41aeb3c28..1bf36898dc7e 100644
> > >>>>> --- a/drivers/gpu/drm/i915/display/intel_color.c
> > >>>>> +++ b/drivers/gpu/drm/i915/display/intel_color.c
> > >>>>> @@ -1076,6 +1076,26 @@ static void skl_get_config(struct intel_crtc_state *crtc_state)
> > >>>>>   		crtc_state->csc_enable = true;
> > >>>>>   }
> > >>>>>   
> > >>>>> +static void icl_get_config(struct intel_crtc_state *crtc_state)
> > >>>>> +{
> > >>>>> +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> > >>>>> +	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
> > >>>>> +	u32 bottom_color;
> > >>>>> +
> > >>>>> +	crtc_state->gamma_mode = hsw_read_gamma_mode(crtc);
> > >>>>> +	crtc_state->csc_mode = ilk_read_csc_mode(crtc);
> > >>>>> +
> > >>>>> +	bottom_color = intel_de_read(i915, SKL_BOTTOM_COLOR(crtc->pipe));
> > >>>>> +
> > >>>>> +	if ((bottom_color & SKL_BOTTOM_COLOR_GAMMA_ENABLE) ||
> > >>>>> +	    (crtc_state->gamma_mode & POST_CSC_GAMMA_ENABLE))
> > >>>>> +		crtc_state->gamma_enable = true;
> > >>>>> +
> > >>>>> +	if ((bottom_color & SKL_BOTTOM_COLOR_CSC_ENABLE) ||
> > >>>>> +	    (crtc_state->csc_mode & ICL_CSC_ENABLE))
> > >>>>> +		crtc_state->csc_enable = true;
> > >>>> We don't use the old per-plane/bottom color way of enabling these.
> > >>>> So this is not right.
> > >>> I think that's the reason for the patch --- today we use
> > >>> skl_get_config() which *only* checks the bottom color settings.  And
> > >>> that approach is documented as being deprecated (although still
> > >>> supported on current platforms).
> > >>>
> > >>> If we're reading out pre-OS state programmed by the vbios, we probably
> > >>> need to handle whichever approach it took, right?  Or are we sanitizing
> > >>> this away to "off" somewhere that makes it okay to miss what was
> > >>> programmed?
> > >> I think we're not doing anything. I suppose some kind of
> > >> assert_legacy_color_stuff_is_off() thing somewhere could be a
> > >> decent addition.
> > > Or maybe we don't need to do anything. The state checker will catch
> > > this problem with the current code as far as the pipe bottom color
> > > is concerned. It won't catch inconsistent plane programming though.
> > > But we also don't have such a consistency check for older platforms
> > > either.
> > 
> > So, are we essentially saying that we can completely remove BOTTOM_COLOR 
> > from here and just move to using GAMMA_MODE, CSC_MODE for setting 
> > gamma_enable and csc_enable?
> 
> No. The current code already works correctly, and pipe_csc_enable and 
> gamma_enable are not meant to be used on icl+.

Then does that mean icl_color_commit_arm() is wrong since we're
programming those registers there?


Matt


> 
> -- 
> Ville Syrjälä
> Intel

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation