Re: [PATCH] drm/i915/display: Check number of scalers for casf

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 11/25/2025 2:37 AM, Ville Syrjälä wrote:
> On Mon, Nov 24, 2025 at 04:39:43PM +0530, Nautiyal, Ankit K wrote:
>> On 11/24/2025 2:16 PM, Nemesa Garg wrote:
>>> Before exposing the property check if the number of scalers
>>> is 2 as casf needs second scaler. If not then dont expose the
>>> property.
>>
>> We are not checking if num_scalers == 2. So the commit message is a bit
>> misleading.
>>
>> Need bit more context:
>>
>> CASF requires the second scaler for sharpness. Skip creating the
>> 'SHARPNESS_STRENGTH' property when num_scalers <= 1.
> Does it really need two scalers always, or just when the first scaler
> is doing actual scaling/etc?

It needs 2nd scaler, the sharpness filter is not there for the 1st scaler.

In platforms where only one scaler per pipe is available, sharpness 
feature cannot work, e.g. HSDES:14018498819.


Regards,

Ankit

>
>> Also, it would be good to align the commit message with this explanation.
>>
>>
>> Regards,
>>
>> Ankit
>>
>>> Signed-off-by: Nemesa Garg <nemesa.garg@intel.com>
>>> ---
>>>    drivers/gpu/drm/i915/display/intel_crtc.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
>>> index 153ff4b4b52c..963e6c7d75b8 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_crtc.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_crtc.c
>>> @@ -395,7 +395,7 @@ int intel_crtc_init(struct intel_display *display, enum pipe pipe)
>>>    
>>>    	drm_WARN_ON(display->drm, drm_crtc_index(&crtc->base) != crtc->pipe);
>>>    
>>> -	if (HAS_CASF(display))
>>> +	if (HAS_CASF(display) && crtc->num_scalers > 1)
>>>    		drm_crtc_create_sharpness_strength_property(&crtc->base);
>>>    
>>>    	return 0;