From: Sean Paul seanpaul@chromium.org
This reverts commit 1dfdb0e107dbe6ebff3f6bbbe4aad0b5aa87bba4.
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. I'm not entirely sure if these have always been isolated to the commit path, but they seem to be now.
[1]- https://lists.freedesktop.org/archives/dri-devel/2019-October/239441.html
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 Signed-off-by: Sean Paul seanpaul@chromium.org --- drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 2 -- drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 1 - 2 files changed, 3 deletions(-)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c index db6c9ccf3be26..c645dd201368b 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c @@ -282,8 +282,6 @@ enum dpu_intf_mode dpu_crtc_get_intf_mode(struct drm_crtc *crtc) return INTF_MODE_NONE; }
- WARN_ON(!drm_modeset_is_locked(&crtc->mutex)); - /* TODO: Returns the first INTF_MODE, could there be multiple values? */ drm_for_each_encoder_mask(encoder, crtc->dev, crtc->state->encoder_mask) return dpu_encoder_get_intf_mode(encoder); diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c index e393a423d7d7a..0e68e20d19c87 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c @@ -305,7 +305,6 @@ 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;
On Thu, Oct 10, 2019 at 5:13 PM Sean Paul sean@poorly.run wrote:
From: Sean Paul seanpaul@chromium.org
This reverts commit 1dfdb0e107dbe6ebff3f6bbbe4aad0b5aa87bba4.
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. I'm not entirely sure if these have always been isolated to the commit path, but they seem to be now.
[1]- https://lists.freedesktop.org/archives/dri-devel/2019-October/239441.html
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 Signed-off-by: Sean Paul seanpaul@chromium.org
drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 2 -- drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 1 - 2 files changed, 3 deletions(-)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c index db6c9ccf3be26..c645dd201368b 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c @@ -282,8 +282,6 @@ enum dpu_intf_mode dpu_crtc_get_intf_mode(struct drm_crtc *crtc) return INTF_MODE_NONE; }
WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
This one is worse ... it's used in two places: - debugfs, where you actually want to make sure you're holding this lock - atomic_check, where this is broken since you're supposed to look at the free-standing states only, except if you really know what you're doing. Given that there's no comment here, I suspect that's not the case. Note that for atomic_check you're guaranteed to hold the modeset lock.
I'd put a FIXME here, but leave the WARN_ON until this is fixed properly.
/* TODO: Returns the first INTF_MODE, could there be multiple values? */ drm_for_each_encoder_mask(encoder, crtc->dev, crtc->state->encoder_mask) return dpu_encoder_get_intf_mode(encoder);diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c index e393a423d7d7a..0e68e20d19c87 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c @@ -305,7 +305,6 @@ 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));
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
but only for this hunk here. -Daniel
drm_for_each_crtc(crtc, dev) { if (!(crtc->state->encoder_mask & drm_encoder_mask(encoder))) continue;-- Sean Paul, Software Engineer, Google / Chromium OS
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;
On Thu, Oct 10, 2019 at 02:17:44PM -0400, Sean Paul wrote:
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
Applied to msm-next with danvet's full irc r-b, thanks for the report and review!
Sean
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;
-- Sean Paul, Software Engineer, Google / Chromium OS
dri-devel@lists.freedesktop.org
-
Daniel Vetter -
Sean Paul