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

[Abhinav Kumar]

Hi Maxime

Gentle reminder on this one.

We are looking for some advice on how to go about KUnit for this static 
function.

Please help with our question below.

Thanks

Abhinav

On 12/6/2024 4:48 PM, Jessica Zhang wrote:
> 
> 
> 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 at 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
>