diff options
Diffstat (limited to 'patches/1592-media-v4l-vsp1-Fix-deadlock-in-VSPDL-DRM-pipelines.patch')
| -rw-r--r-- | patches/1592-media-v4l-vsp1-Fix-deadlock-in-VSPDL-DRM-pipelines.patch | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/patches/1592-media-v4l-vsp1-Fix-deadlock-in-VSPDL-DRM-pipelines.patch b/patches/1592-media-v4l-vsp1-Fix-deadlock-in-VSPDL-DRM-pipelines.patch new file mode 100644 index 00000000000000..dbab06845154c9 --- /dev/null +++ b/patches/1592-media-v4l-vsp1-Fix-deadlock-in-VSPDL-DRM-pipelines.patch @@ -0,0 +1,72 @@ +From 3d59169bdb54c2322a1c19f62dad601597c8116f Mon Sep 17 00:00:00 2001 +From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> +Date: Fri, 27 Jul 2018 13:19:45 -0400 +Subject: [PATCH 1592/1795] media: v4l: vsp1: Fix deadlock in VSPDL DRM + pipelines + +The VSP uses a lock to protect the BRU and BRS assignment when +configuring pipelines. The lock is taken in vsp1_du_atomic_begin() and +released in vsp1_du_atomic_flush(), as well as taken and released in +vsp1_du_setup_lif(). This guards against multiple pipelines trying to +assign the same BRU and BRS at the same time. + +The DRM framework calls the .atomic_begin() operations in a loop over +all CRTCs included in an atomic commit. On a VSPDL (the only VSP type +where this matters), a single VSP instance handles two CRTCs, with a +single lock. This results in a deadlock when the .atomic_begin() +operation is called on the second CRTC. + +The DRM framework serializes atomic commits that affect the same CRTCs, +but doesn't know about two CRTCs sharing the same VSPDL. Two commits +affecting the VSPDL LIF0 and LIF1 respectively can thus race each other, +hence the need for a lock. + +This could be fixed on the DRM side by forcing serialization of commits +affecting CRTCs backed by the same VSPDL, but that would negatively +affect performances, as the locking is only needed when the BRU and BRS +need to be reassigned, which is an uncommon case. + +The lock protects the whole .atomic_begin() to .atomic_flush() sequence. +The only operation that can occur in-between is vsp1_du_atomic_update(), +which doesn't touch the BRU and BRS, and thus doesn't need to be +protected by the lock. We can thus only take the lock around the +pipeline setup calls in vsp1_du_atomic_flush(), which fixes the +deadlock. + +Fixes: f81f9adc4ee1 ("media: v4l: vsp1: Assign BRU and BRS to pipelines dynamically") + +Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> +Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com> +Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> +(cherry picked from commit 8eb0e6421958e9777db98448a4030d8ae940c9a0) +Signed-off-by: Simon Horman <horms+renesas@verge.net.au> +Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> +--- + drivers/media/platform/vsp1/vsp1_drm.c | 4 +--- + 1 file changed, 1 insertion(+), 3 deletions(-) + +diff --git a/drivers/media/platform/vsp1/vsp1_drm.c b/drivers/media/platform/vsp1/vsp1_drm.c +index edb35a5c57ea..a99fc0ced7a7 100644 +--- a/drivers/media/platform/vsp1/vsp1_drm.c ++++ b/drivers/media/platform/vsp1/vsp1_drm.c +@@ -728,9 +728,6 @@ EXPORT_SYMBOL_GPL(vsp1_du_setup_lif); + */ + void vsp1_du_atomic_begin(struct device *dev, unsigned int pipe_index) + { +- struct vsp1_device *vsp1 = dev_get_drvdata(dev); +- +- mutex_lock(&vsp1->drm->lock); + } + EXPORT_SYMBOL_GPL(vsp1_du_atomic_begin); + +@@ -846,6 +843,7 @@ void vsp1_du_atomic_flush(struct device *dev, unsigned int pipe_index, + + drm_pipe->crc = cfg->crc; + ++ mutex_lock(&vsp1->drm->lock); + vsp1_du_pipeline_setup_inputs(vsp1, pipe); + vsp1_du_pipeline_configure(pipe); + mutex_unlock(&vsp1->drm->lock); +-- +2.19.0 + |