From: Sean Paul seanpaul@chromium.org
As Daniel mentions in his email [1], non-blocking commits don't hold the modeset locks, so we can safely access state as long as these functions are in the commit path. So remove the WARN_ON in dpu_kms_encoder_enable.
In dpu_crtc_get_intf_mode, things are a bit more complicated. So keep the WARN_ON, but add a comment explaining the situation and hope someone comes along and fixes the issue.
[1]- https://lists.freedesktop.org/archives/dri-devel/2019-October/239441.html
Link to v1: https://patchwork.freedesktop.org/patch/msgid/20191010151351.126735-1-sean@p...
Changes in v2: - Restored the WARN_ON in get_intf_mode and added a clarifying comment (Daniel)
Fixes: 1dfdb0e107db ("drm/msm: dpu: Add modeset lock checks where applicable") Cc: Jeykumar Sankaran jsanka@codeaurora.org Cc: Rob Clark robdclark@chromium.org Suggested-by: Daniel Vetter daniel@ffwll.ch Partially-Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Sean Paul seanpaul@chromium.org --- drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 9 +++++++++ drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 1 - 2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c index 0b9dc042d2e22..f197dce545761 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c @@ -271,6 +271,15 @@ enum dpu_intf_mode dpu_crtc_get_intf_mode(struct drm_crtc *crtc) return INTF_MODE_NONE; }
+ /* + * TODO: This function is called from dpu debugfs and as part of atomic + * check. When called from debugfs, the crtc->mutex must be held to + * read crtc->state. However reading crtc->state from atomic check isn't + * allowed (unless you have a good reason, a big comment, and a deep + * understanding of how the atomic/modeset locks work (<- and this is + * probably not possible)). So we'll keep the WARN_ON here for now, but + * really we need to figure out a better way to track our operating mode + */ WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
/* TODO: Returns the first INTF_MODE, could there be multiple values? */ diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c index b1645ad83a1e1..6c92f0fbeac98 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c @@ -316,7 +316,6 @@ void dpu_kms_encoder_enable(struct drm_encoder *encoder) if (funcs && funcs->commit) funcs->commit(encoder);
- WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex)); drm_for_each_crtc(crtc, dev) { if (!(crtc->state->encoder_mask & drm_encoder_mask(encoder))) continue;