[bug report] drm: Add helpers to kick off self refresh mode in drivers

[Dan Carpenter]

On Wed, Jun 19, 2019 at 12:39:37PM +0300, Dan Carpenter wrote:
>     72          int i, ret;
>     73  
>     74          drm_modeset_acquire_init(&ctx, 0);
>     75  
>     76          state = drm_atomic_state_alloc(dev);
>     77          if (!state) {
>     78                  ret = -ENOMEM;
>     79                  goto out;
>                         ^^^^^^^^
> The allocation failed.
> 
>     80          }
>     81  
>     82  retry:
>     83          state->acquire_ctx = &ctx;
>     84  
>     85          crtc_state = drm_atomic_get_crtc_state(state, crtc);
>     86          if (IS_ERR(crtc_state)) {
>     87                  ret = PTR_ERR(crtc_state);
>     88                  goto out;
>     89          }
>     90  
>     91          if (!crtc_state->enable)
>     92                  goto out;

Oh...  Also we need to set "ret" here.

>     93  
>     94          ret = drm_atomic_add_affected_connectors(state, crtc);
>     95          if (ret)
>     96                  goto out;
>     97  
>     98          for_each_new_connector_in_state(state, conn, conn_state, i) {
>     99                  if (!conn_state->self_refresh_aware)
>    100                          goto out;
>    101          }
>    102  
>    103          crtc_state->active = false;
>    104          crtc_state->self_refresh_active = true;
>    105  
>    106          ret = drm_atomic_commit(state);
>    107          if (ret)
>    108                  goto out;
>    109  
>    110  out:
>    111          if (ret == -EDEADLK) {
>    112                  drm_atomic_state_clear(state);
>    113                  ret = drm_modeset_backoff(&ctx);
>    114                  if (!ret)
>    115                          goto retry;
>    116          }
>    117  
>    118          drm_atomic_state_put(state);
>                                      ^^^^^
> NULL dereference.
> 
>    119          drm_modeset_drop_locks(&ctx);
>    120          drm_modeset_acquire_fini(&ctx);
>    121  }

regards,
dan carpenter