On 7/9/2024 6:48 AM, Dmitry Baryshkov wrote:
In order to prevent any errors on connector being disabled, move the
state->crtc check upfront. This should fix the issues during suspend
when the writeback connector gets forcebly disabled.

Fixes: 71174f362d67 ("drm/msm/dpu: move writeback's atomic_check to 
dpu_writeback.c")
Cc: sta...@vger.kernel.org
Reported-by: Leonard Lausen <leon...@lausen.nl>
Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/57
Signed-off-by: Dmitry Baryshkov <dmitry.barysh...@linaro.org>
---
  drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c | 14 +++++++-------
  1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c 
b/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
index 16f144cbc0c9..5c172bcf3419 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_writeback.c
@@ -39,6 +39,13 @@ static int dpu_wb_conn_atomic_check(struct drm_connector 
*connector,
DPU_DEBUG("[atomic_check:%d]\n", connector->base.id); + crtc = conn_state->crtc;

We are checking for !conn_state a few lines below but we are dereferencing conn_state here.

This is bound to hit a smatch error and also does not look right.

If conn_state will always be valid, we should drop that check too rather than checking it later.

Coming to the issue itself, I tried checking the logs but it was not clear.

During force disable, were we hitting below check and hence the connector was not getting disabled?

else if (conn_state->connector->status != connector_status_connected) {
DPU_ERROR("connector not connected %d\n", conn_state->connector->status);
                return -EINVAL;
        }


I did not see this error log there, so can you pls explain where we were bailing out? The check seems valid to me.

+       if (!crtc)
+               return 0;
+
+       if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
+               return 0;
+
        if (!conn_state || !conn_state->connector) {
                DPU_ERROR("invalid connector state\n");
                return -EINVAL;
@@ -47,13 +54,6 @@ static int dpu_wb_conn_atomic_check(struct drm_connector 
*connector,
                return -EINVAL;
        }
- crtc = conn_state->crtc;
-       if (!crtc)
-               return 0;
-
-       if (!conn_state->writeback_job || !conn_state->writeback_job->fb)
-               return 0;
-
        crtc_state = drm_atomic_get_crtc_state(state, crtc);
        if (IS_ERR(crtc_state))
                return PTR_ERR(crtc_state);

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