[PATCH AUTOSEL 6.7 57/88] drm/msm/dpu: Add mutex lock in control vblank irq

Sasha Levin
2024-01-22T14:59:45Z

From: Paloma Arellano <quic_parellan@quicinc.com>

[ Upstream commit 45284ff733e4caf6c118aae5131eb7e7cf3eea5a ]

Add a mutex lock to control vblank irq to synchronize vblank
enable/disable operations happening from different threads to prevent
race conditions while registering/unregistering the vblank irq callback.

v4: -Removed vblank_ctl_lock from dpu_encoder_virt, so it is only a
parameter of dpu_encoder_phys.
-Switch from atomic refcnt to a simple int counter as mutex has
now been added
v3: Mistakenly did not change wording in last version. It is done now.
v2: Slightly changed wording of commit message

Signed-off-by: Paloma Arellano <quic_parellan@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/571854/
Link: https://lore.kernel.org/r/20231212231101.9240-2-quic_parellan@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 1 -
.../gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h | 4 ++-
.../drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c | 32 ++++++++++++------
.../drm/msm/disp/dpu1/dpu_encoder_phys_vid.c | 33 ++++++++++++-------
4 files changed, 47 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
index ff0e3591b44d..289e4a615a08 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
@@ -2500,7 +2500,6 @@ void dpu_encoder_phys_init(struct dpu_encoder_phys *phys_enc,
phys_enc->enc_spinlock = p->enc_spinlock;
phys_enc->enable_state = DPU_ENC_DISABLED;

- atomic_set(&phys_enc->vblank_refcount, 0);
atomic_set(&phys_enc->pending_kickoff_cnt, 0);
atomic_set(&phys_enc->pending_ctlstart_cnt, 0);

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
index 6f04c3d56e77..96bda57b6959 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
@@ -155,6 +155,7 @@ enum dpu_intr_idx {
* @hw_wb: Hardware interface to the wb registers
* @dpu_kms: Pointer to the dpu_kms top level
* @cached_mode: DRM mode cached at mode_set time, acted on in enable
+ * @vblank_ctl_lock: Vblank ctl mutex lock to protect vblank_refcount
* @enabled: Whether the encoder has enabled and running a mode
* @split_role: Role to play in a split-panel configuration
* @intf_mode: Interface mode
@@ -183,11 +184,12 @@ struct dpu_encoder_phys {
struct dpu_hw_wb *hw_wb;
struct dpu_kms *dpu_kms;
struct drm_display_mode cached_mode;
+ struct mutex vblank_ctl_lock;
enum dpu_enc_split_role split_role;
enum dpu_intf_mode intf_mode;
spinlock_t *enc_spinlock;
enum dpu_enc_enable_state enable_state;
- atomic_t vblank_refcount;
+ int vblank_refcount;
atomic_t vsync_cnt;
atomic_t underrun_cnt;
atomic_t pending_ctlstart_cnt;
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
index be185fe69793..2d788c5e26a8 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
@@ -244,7 +244,8 @@ static int dpu_encoder_phys_cmd_control_vblank_irq(
return -EINVAL;
}

- refcount = atomic_read(&phys_enc->vblank_refcount);
+ mutex_lock(&phys_enc->vblank_ctl_lock);
+ refcount = phys_enc->vblank_refcount;

/* Slave encoders don't report vblank */
if (!dpu_encoder_phys_cmd_is_master(phys_enc))
@@ -260,16 +261,24 @@ static int dpu_encoder_phys_cmd_control_vblank_irq(
phys_enc->hw_pp->idx - PINGPONG_0,
enable ? "true" : "false", refcount);

- if (enable && atomic_inc_return(&phys_enc->vblank_refcount) == 1)
- ret = dpu_core_irq_register_callback(phys_enc->dpu_kms,
- phys_enc->irq[INTR_IDX_RDPTR],
- dpu_encoder_phys_cmd_te_rd_ptr_irq,
- phys_enc);
- else if (!enable && atomic_dec_return(&phys_enc->vblank_refcount) == 0)
- ret = dpu_core_irq_unregister_callback(phys_enc->dpu_kms,
- phys_enc->irq[INTR_IDX_RDPTR]);
+ if (enable) {
+ if (phys_enc->vblank_refcount == 0)
+ ret = dpu_core_irq_register_callback(phys_enc->dpu_kms,
+ phys_enc->irq[INTR_IDX_RDPTR],
+ dpu_encoder_phys_cmd_te_rd_ptr_irq,
+ phys_enc);
+ if (!ret)
+ phys_enc->vblank_refcount++;
+ } else if (!enable) {
+ if (phys_enc->vblank_refcount == 1)
+ ret = dpu_core_irq_unregister_callback(phys_enc->dpu_kms,
+ phys_enc->irq[INTR_IDX_RDPTR]);
+ if (!ret)
+ phys_enc->vblank_refcount--;
+ }

end:
+ mutex_unlock(&phys_enc->vblank_ctl_lock);
if (ret) {
DRM_ERROR("vblank irq err id:%u pp:%d ret:%d, enable %s/%d\n",
DRMID(phys_enc->parent),
@@ -285,7 +294,7 @@ static void dpu_encoder_phys_cmd_irq_control(struct dpu_encoder_phys *phys_enc,
{
trace_dpu_enc_phys_cmd_irq_ctrl(DRMID(phys_enc->parent),
phys_enc->hw_pp->idx - PINGPONG_0,
- enable, atomic_read(&phys_enc->vblank_refcount));
+ enable, phys_enc->vblank_refcount);

if (enable) {
dpu_core_irq_register_callback(phys_enc->dpu_kms,
@@ -763,6 +772,9 @@ struct dpu_encoder_phys *dpu_encoder_phys_cmd_init(

dpu_encoder_phys_init(phys_enc, p);

+ mutex_init(&phys_enc->vblank_ctl_lock);
+ phys_enc->vblank_refcount = 0;
+
dpu_encoder_phys_cmd_init_ops(&phys_enc->ops);
phys_enc->intf_mode = INTF_MODE_CMD;
cmd_enc->stream_sel = 0;
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
index a01fda711883..eeb0acf9665e 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
@@ -364,7 +364,8 @@ static int dpu_encoder_phys_vid_control_vblank_irq(
int ret = 0;
int refcount;

- refcount = atomic_read(&phys_enc->vblank_refcount);
+ mutex_lock(&phys_enc->vblank_ctl_lock);
+ refcount = phys_enc->vblank_refcount;

/* Slave encoders don't report vblank */
if (!dpu_encoder_phys_vid_is_master(phys_enc))
@@ -377,18 +378,26 @@ static int dpu_encoder_phys_vid_control_vblank_irq(
}

DRM_DEBUG_VBL("id:%u enable=%d/%d\n", DRMID(phys_enc->parent), enable,
- atomic_read(&phys_enc->vblank_refcount));
+ refcount);

- if (enable && atomic_inc_return(&phys_enc->vblank_refcount) == 1)
- ret = dpu_core_irq_register_callback(phys_enc->dpu_kms,
- phys_enc->irq[INTR_IDX_VSYNC],
- dpu_encoder_phys_vid_vblank_irq,
- phys_enc);
- else if (!enable && atomic_dec_return(&phys_enc->vblank_refcount) == 0)
- ret = dpu_core_irq_unregister_callback(phys_enc->dpu_kms,
- phys_enc->irq[INTR_IDX_VSYNC]);
+ if (enable) {
+ if (phys_enc->vblank_refcount == 0)
+ ret = dpu_core_irq_register_callback(phys_enc->dpu_kms,
+ phys_enc->irq[INTR_IDX_VSYNC],
+ dpu_encoder_phys_vid_vblank_irq,
+ phys_enc);
+ if (!ret)
+ phys_enc->vblank_refcount++;
+ } else if (!enable) {
+ if (phys_enc->vblank_refcount == 1)
+ ret = dpu_core_irq_unregister_callback(phys_enc->dpu_kms,
+ phys_enc->irq[INTR_IDX_VSYNC]);
+ if (!ret)
+ phys_enc->vblank_refcount--;
+ }

end:
+ mutex_unlock(&phys_enc->vblank_ctl_lock);
if (ret) {
DRM_ERROR("failed: id:%u intf:%d ret:%d enable:%d refcnt:%d\n",
DRMID(phys_enc->parent),
@@ -618,7 +627,7 @@ static void dpu_encoder_phys_vid_irq_control(struct dpu_encoder_phys *phys_enc,
trace_dpu_enc_phys_vid_irq_ctrl(DRMID(phys_enc->parent),
phys_enc->hw_intf->idx - INTF_0,
enable,
- atomic_read(&phys_enc->vblank_refcount));
+ phys_enc->vblank_refcount);

if (enable) {
ret = dpu_encoder_phys_vid_control_vblank_irq(phys_enc, true);
@@ -713,6 +722,8 @@ struct dpu_encoder_phys *dpu_encoder_phys_vid_init(
DPU_DEBUG_VIDENC(phys_enc, "\n");

dpu_encoder_phys_init(phys_enc, p);
+ mutex_init(&phys_enc->vblank_ctl_lock);
+ phys_enc->vblank_refcount = 0;

dpu_encoder_phys_vid_init_ops(&phys_enc->ops);
phys_enc->intf_mode = INTF_MODE_VIDEO;
--
2.43.0