drm/msm/dpu: rate limit snapshot capture for mmu faults

There is no recovery mechanism in place yet to recover from mmu
faults for DPU. We can only prevent the faults by making sure there
is no misconfiguration.

Rate-limit the snapshot capture for mmu faults to once per
msm_atomic_commit_tail() as that should be sufficient to capture
the snapshot for debugging otherwise there will be a lot of DPU
snapshots getting captured for the same fault which is redundant
and also might affect capturing even one snapshot accurately.

Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/638362/
Link: https://lore.kernel.org/r/20250219-abhinavk-smmu-fault-handler-v3-5-aa3f0bf4434a@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
index a7a2384044ffdb13579cc9a10f56f8de9beca761..83c4e6aca20951b0f5616764f99c39cdaf524593 100644 (file)
--- a/drivers/gpu/drm/msm/msm_atomic.c
+++ b/drivers/gpu/drm/msm/msm_atomic.c
@@ -221,6 +221,8 @@ void msm_atomic_commit_tail(struct drm_atomic_state *state)
        kms->funcs->wait_flush(kms, crtc_mask);
        trace_msm_atomic_wait_flush_finish(crtc_mask);
 
+       atomic_set(&kms->fault_snapshot_capture, 0);
+
        /*
         * Now that there is no in-progress flush, prepare the
         * current update:

diff --git a/drivers/gpu/drm/msm/msm_kms.c b/drivers/gpu/drm/msm/msm_kms.c
index 35b835e0f23aff8063a9b2ffba9f24e5cbf441ff..b877278888e6228a84773e0dd6c4fc8ce24b2de6 100644 (file)
--- a/drivers/gpu/drm/msm/msm_kms.c
+++ b/drivers/gpu/drm/msm/msm_kms.c
@@ -168,7 +168,10 @@ static int msm_kms_fault_handler(void *arg, unsigned long iova, int flags, void
 {
        struct msm_kms *kms = arg;
 
-       msm_disp_snapshot_state(kms->dev);
+       if (atomic_read(&kms->fault_snapshot_capture) == 0) {
+               msm_disp_snapshot_state(kms->dev);
+               atomic_inc(&kms->fault_snapshot_capture);
+       }
 
        return -ENOSYS;
 }

diff --git a/drivers/gpu/drm/msm/msm_kms.h b/drivers/gpu/drm/msm/msm_kms.h
index e60162744c669773b6e5aef824a173647626ab4e..3e28c4e012d2be6fd5af11324e13249623431697 100644 (file)
--- a/drivers/gpu/drm/msm/msm_kms.h
+++ b/drivers/gpu/drm/msm/msm_kms.h
@@ -128,6 +128,9 @@ struct msm_kms {
        int irq;
        bool irq_requested;
 
+       /* rate limit the snapshot capture to once per attach */
+       atomic_t fault_snapshot_capture;
+
        /* mapper-id used to request GEM buffer mapped for scanout: */
        struct msm_gem_address_space *aspace;