From ab198a7aab65d6fcdbde082ff59a790dbf7e08f4 Mon Sep 17 00:00:00 2001 From: Sean Paul Date: Thu, 10 Oct 2019 14:17:44 -0400 Subject: [PATCH] drm/msm: Sanitize the modeset_is_locked checks in dpu 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@poorly.run 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 Cc: Rob Clark Suggested-by: Daniel Vetter Reviewed-by: Daniel Vetter Signed-off-by: Sean Paul Link: https://patchwork.freedesktop.org/patch/msgid/20191010181801.186069-1-sean@poorly.run --- 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 0b9dc042d2e2..f197dce54576 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 b1645ad83a1e..6c92f0fbeac9 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; -- 2.45.2