[PATCH] drm/msm/dpu: Delete bonkers code

From: Rob Clark
Date: Fri Apr 30 2021 - 13:14:14 EST


From: Rob Clark <robdclark@xxxxxxxxxxxx>

dpu_crtc_atomic_flush() was directly poking it's attached planes in a
code path that ended up in dpu_plane_atomic_update(), even if the plane
was not involved in the current atomic update. While a bit dubious,
this worked before because plane->state would always point to something
valid. But now using drm_atomic_get_new_plane_state() we could get a
NULL state pointer instead, leading to:

[ 20.873273] Call trace:
[ 20.875740] dpu_plane_atomic_update+0x5c/0xed0
[ 20.880311] dpu_plane_restore+0x40/0x88
[ 20.884266] dpu_crtc_atomic_flush+0xf4/0x208
[ 20.888660] drm_atomic_helper_commit_planes+0x150/0x238
[ 20.894014] msm_atomic_commit_tail+0x1d4/0x7a0
[ 20.898579] commit_tail+0xa4/0x168
[ 20.902102] drm_atomic_helper_commit+0x164/0x178
[ 20.906841] drm_atomic_commit+0x54/0x60
[ 20.910798] drm_atomic_connector_commit_dpms+0x10c/0x118
[ 20.916236] drm_mode_obj_set_property_ioctl+0x1e4/0x440
[ 20.921588] drm_connector_property_set_ioctl+0x60/0x88
[ 20.926852] drm_ioctl_kernel+0xd0/0x120
[ 20.930807] drm_ioctl+0x21c/0x478
[ 20.934235] __arm64_sys_ioctl+0xa8/0xe0
[ 20.938193] invoke_syscall+0x64/0x130
[ 20.941977] el0_svc_common.constprop.3+0x5c/0xe0
[ 20.946716] do_el0_svc+0x80/0xa0
[ 20.950058] el0_svc+0x20/0x30
[ 20.953145] el0_sync_handler+0x88/0xb0
[ 20.957014] el0_sync+0x13c/0x140

The reason for the codepath seems dubious, the atomic suspend/resume
heplers should handle the power-collapse case. If not, the CRTC's
atomic_check() should be adding the planes to the atomic update.

Reported-by: Stephen Boyd <sboyd@xxxxxxxxxx>
Reported-by: John Stultz <john.stultz@xxxxxxxxxx>
Fixes: 37418bf14c13 drm: Use state helper instead of the plane state pointer
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 10 ----------
drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 16 ----------------
drivers/gpu/drm/msm/disp/dpu1/dpu_plane.h | 6 ------
3 files changed, 32 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
index 7c29976be243..18bc76b7f1a3 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
@@ -648,16 +648,6 @@ static void dpu_crtc_atomic_flush(struct drm_crtc *crtc,
if (unlikely(!cstate->num_mixers))
return;

- /*
- * For planes without commit update, drm framework will not add
- * those planes to current state since hardware update is not
- * required. However, if those planes were power collapsed since
- * last commit cycle, driver has to restore the hardware state
- * of those planes explicitly here prior to plane flush.
- */
- drm_atomic_crtc_for_each_plane(plane, crtc)
- dpu_plane_restore(plane, state);
-
/* update performance setting before crtc kickoff */
dpu_core_perf_crtc_update(crtc, 1, false);

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
index df7f3d3afd8b..7a993547eb75 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
@@ -1258,22 +1258,6 @@ static void dpu_plane_atomic_update(struct drm_plane *plane,
}
}

-void dpu_plane_restore(struct drm_plane *plane, struct drm_atomic_state *state)
-{
- struct dpu_plane *pdpu;
-
- if (!plane || !plane->state) {
- DPU_ERROR("invalid plane\n");
- return;
- }
-
- pdpu = to_dpu_plane(plane);
-
- DPU_DEBUG_PLANE(pdpu, "\n");
-
- dpu_plane_atomic_update(plane, state);
-}
-
static void dpu_plane_destroy(struct drm_plane *plane)
{
struct dpu_plane *pdpu = plane ? to_dpu_plane(plane) : NULL;
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.h
index 03b6365a750c..34e03ac05f4a 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.h
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.h
@@ -84,12 +84,6 @@ bool is_dpu_plane_virtual(struct drm_plane *plane);
void dpu_plane_get_ctl_flush(struct drm_plane *plane, struct dpu_hw_ctl *ctl,
u32 *flush_sspp);

-/**
- * dpu_plane_restore - restore hw state if previously power collapsed
- * @plane: Pointer to drm plane structure
- */
-void dpu_plane_restore(struct drm_plane *plane, struct drm_atomic_state *state);
-
/**
* dpu_plane_flush - final plane operations before commit flush
* @plane: Pointer to drm plane structure
--
2.30.2