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

[Pottumuttu, Sai Teja]

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?