Re: [PATCH v2 02/22] drm: Add valid clones check

[Jessica Zhang <quic_jesszhan@quicinc.com>]

On 9/25/2024 12:23 AM, Maxime Ripard wrote:
> On Tue, Sep 24, 2024 at 03:59:18PM GMT, Jessica Zhang wrote:
>> Check that all encoders attached to a given CRTC are valid
>> possible_clones of each other.
>>
>> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
>> ---
>>   drivers/gpu/drm/drm_atomic_helper.c | 23 +++++++++++++++++++++++
>>   1 file changed, 23 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
>> index 43cdf39019a4..cc4001804fdc 100644
>> --- a/drivers/gpu/drm/drm_atomic_helper.c
>> +++ b/drivers/gpu/drm/drm_atomic_helper.c
>> @@ -574,6 +574,25 @@ mode_valid(struct drm_atomic_state *state)
>>   	return 0;
>>   }
>>   
>> +static int drm_atomic_check_valid_clones(struct drm_atomic_state *state,
>> +					 struct drm_crtc *crtc)
>> +{
>> +	struct drm_encoder *drm_enc;
>> +	struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state,
>> +									  crtc);
>> +
>> +	drm_for_each_encoder_mask(drm_enc, crtc->dev, crtc_state->encoder_mask) {
>> +		if ((crtc_state->encoder_mask & drm_enc->possible_clones) !=
>> +		    crtc_state->encoder_mask) {
>> +			DRM_DEBUG("crtc%d failed valid clone check for mask 0x%x\n",
>> +				  crtc->base.id, crtc_state->encoder_mask);
>> +			return -EINVAL;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>   /**
>>    * drm_atomic_helper_check_modeset - validate state object for modeset changes
>>    * @dev: DRM device
>> @@ -745,6 +764,10 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
>>   		ret = drm_atomic_add_affected_planes(state, crtc);
>>   		if (ret != 0)
>>   			return ret;
>> +
>> +		ret = drm_atomic_check_valid_clones(state, crtc);
>> +		if (ret != 0)
>> +			return ret;
>>   	}
> 
> Pretty much the same comment, we should have kunit tests for this.

Hey Maxime,

I'm working on the kunit test for this and had a question on the design 
for the unit test:

Since this is a static helper that returns a pretty common error code, 
how would you recommend going about making sure that 
`drm_atomic_check_valid_clones()` specifically is returning the error 
(and not a different part of check_modeset) when testing the 
check_valid_clones() failure path?

Thanks,

Jessica Zhang

> 
> Maxime