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_jessz...@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

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