Re: [PATCH v2] Revert "drm/msm/dpu: drop dpu_encoder_phys_ops.atomic_mode_set"

[Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>]

On 5/22/2024 3:24 AM, Dmitry Baryshkov wrote:
> In the DPU driver blank IRQ handling is called from a vblank worker and
> can happen outside of the irq_enable / irq_disable pair. Using the
> worker makes that completely asynchronous with the rest of the code.
> Revert commit d13f638c9b88 ("drm/msm/dpu: drop
> dpu_encoder_phys_ops.atomic_mode_set") to fix vblank IRQ assignment for
> CMD DSI panels.
>
> Call trace:
>   dpu_encoder_phys_cmd_control_vblank_irq+0x218/0x294
>    dpu_encoder_toggle_vblank_for_crtc+0x160/0x194
>    dpu_crtc_vblank+0xbc/0x228
>    dpu_kms_enable_vblank+0x18/0x24
>    vblank_ctrl_worker+0x34/0x6c
>    process_one_work+0x218/0x620
>    worker_thread+0x1ac/0x37c
>    kthread+0x114/0x118
>    ret_from_fork+0x10/0x20

Thanks for the stack.

Agreed that vblank can be controlled asynchronously through the worker.

And I am guessing that the worker thread ran and printed this error 
message because phys_enc->irq[INTR_IDX_VSYNC] was not valid as modeset 
had not happened by then?

272 end:
273 	if (ret) {
274 		DRM_ERROR("vblank irq err id:%u pp:%d ret:%d, enable %s/%d\n",
275 			  DRMID(phys_enc->parent),
276 			  phys_enc->hw_pp->idx - PINGPONG_0, ret,
277 			  enable ? "true" : "false", refcount);
278 	}

But how come this did not happen even with this revert.

IOW, I am still missing how moving the irq assignment back to modeset 
from enable is fixing this?

> Fixes: d13f638c9b88 ("drm/msm/dpu: drop dpu_encoder_phys_ops.atomic_mode_set")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
> Changes in v2:
> - Expanded commit message to describe the reason for revert and added a
>    call trace (Abhinav)
> - Link to v1: https://lore.kernel.org/r/20240514-dpu-revert-ams-v1-1-b13623d6cd5f@xxxxxxxxxx
> ---
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c        |  2 ++
>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h   |  5 ++++
>   .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c   | 32 ++++++++++++----------
>   .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c   | 13 +++++++--
>   .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c    | 11 +++++++-
>   5 files changed, 46 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index 119f3ea50a7c..a7d8ecf3f5be 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -1200,6 +1200,8 @@ static void dpu_encoder_virt_atomic_mode_set(struct drm_encoder *drm_enc,
>   		phys->hw_ctl = to_dpu_hw_ctl(hw_ctl[i]);
>   
>   		phys->cached_mode = crtc_state->adjusted_mode;
> +		if (phys->ops.atomic_mode_set)
> +			phys->ops.atomic_mode_set(phys, crtc_state, conn_state);
>   	}
>   }
>   
> 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 002e89cc1705..30470cd15a48 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
> @@ -69,6 +69,8 @@ struct dpu_encoder_phys;
>    * @is_master:			Whether this phys_enc is the current master
>    *				encoder. Can be switched at enable time. Based
>    *				on split_role and current mode (CMD/VID).
> + * @atomic_mode_set:		DRM Call. Set a DRM mode.
> + *				This likely caches the mode, for use at enable.
>    * @enable:			DRM Call. Enable a DRM mode.
>    * @disable:			DRM Call. Disable mode.
>    * @control_vblank_irq		Register/Deregister for VBLANK IRQ
> @@ -93,6 +95,9 @@ struct dpu_encoder_phys;
>   struct dpu_encoder_phys_ops {
>   	void (*prepare_commit)(struct dpu_encoder_phys *encoder);
>   	bool (*is_master)(struct dpu_encoder_phys *encoder);
> +	void (*atomic_mode_set)(struct dpu_encoder_phys *encoder,
> +			struct drm_crtc_state *crtc_state,
> +			struct drm_connector_state *conn_state);
>   	void (*enable)(struct dpu_encoder_phys *encoder);
>   	void (*disable)(struct dpu_encoder_phys *encoder);
>   	int (*control_vblank_irq)(struct dpu_encoder_phys *enc, bool enable);
> 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 489be1c0c704..95cd39b49668 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
> @@ -142,6 +142,23 @@ static void dpu_encoder_phys_cmd_underrun_irq(void *arg)
>   	dpu_encoder_underrun_callback(phys_enc->parent, phys_enc);
>   }
>   
> +static void dpu_encoder_phys_cmd_atomic_mode_set(
> +		struct dpu_encoder_phys *phys_enc,
> +		struct drm_crtc_state *crtc_state,
> +		struct drm_connector_state *conn_state)
> +{
> +	phys_enc->irq[INTR_IDX_CTL_START] = phys_enc->hw_ctl->caps->intr_start;
> +
> +	phys_enc->irq[INTR_IDX_PINGPONG] = phys_enc->hw_pp->caps->intr_done;
> +
> +	if (phys_enc->has_intf_te)
> +		phys_enc->irq[INTR_IDX_RDPTR] = phys_enc->hw_intf->cap->intr_tear_rd_ptr;
> +	else
> +		phys_enc->irq[INTR_IDX_RDPTR] = phys_enc->hw_pp->caps->intr_rdptr;
> +
> +	phys_enc->irq[INTR_IDX_UNDERRUN] = phys_enc->hw_intf->cap->intr_underrun;
> +}
> +
>   static int _dpu_encoder_phys_cmd_handle_ppdone_timeout(
>   		struct dpu_encoder_phys *phys_enc)
>   {
> @@ -280,14 +297,6 @@ static void dpu_encoder_phys_cmd_irq_enable(struct dpu_encoder_phys *phys_enc)
>   					  phys_enc->hw_pp->idx - PINGPONG_0,
>   					  phys_enc->vblank_refcount);
>   
> -	phys_enc->irq[INTR_IDX_CTL_START] = phys_enc->hw_ctl->caps->intr_start;
> -	phys_enc->irq[INTR_IDX_PINGPONG] = phys_enc->hw_pp->caps->intr_done;
> -
> -	if (phys_enc->has_intf_te)
> -		phys_enc->irq[INTR_IDX_RDPTR] = phys_enc->hw_intf->cap->intr_tear_rd_ptr;
> -	else
> -		phys_enc->irq[INTR_IDX_RDPTR] = phys_enc->hw_pp->caps->intr_rdptr;
> -
>   	dpu_core_irq_register_callback(phys_enc->dpu_kms,
>   				       phys_enc->irq[INTR_IDX_PINGPONG],
>   				       dpu_encoder_phys_cmd_pp_tx_done_irq,
> @@ -318,10 +327,6 @@ static void dpu_encoder_phys_cmd_irq_disable(struct dpu_encoder_phys *phys_enc)
>   	dpu_core_irq_unregister_callback(phys_enc->dpu_kms, phys_enc->irq[INTR_IDX_UNDERRUN]);
>   	dpu_encoder_phys_cmd_control_vblank_irq(phys_enc, false);
>   	dpu_core_irq_unregister_callback(phys_enc->dpu_kms, phys_enc->irq[INTR_IDX_PINGPONG]);
> -
> -	phys_enc->irq[INTR_IDX_CTL_START] = 0;
> -	phys_enc->irq[INTR_IDX_PINGPONG] = 0;
> -	phys_enc->irq[INTR_IDX_RDPTR] = 0;
>   }
>   
>   static void dpu_encoder_phys_cmd_tearcheck_config(
> @@ -698,6 +703,7 @@ static void dpu_encoder_phys_cmd_init_ops(
>   		struct dpu_encoder_phys_ops *ops)
>   {
>   	ops->is_master = dpu_encoder_phys_cmd_is_master;
> +	ops->atomic_mode_set = dpu_encoder_phys_cmd_atomic_mode_set;
>   	ops->enable = dpu_encoder_phys_cmd_enable;
>   	ops->disable = dpu_encoder_phys_cmd_disable;
>   	ops->control_vblank_irq = dpu_encoder_phys_cmd_control_vblank_irq;
> @@ -736,8 +742,6 @@ struct dpu_encoder_phys *dpu_encoder_phys_cmd_init(struct drm_device *dev,
>   
>   	dpu_encoder_phys_cmd_init_ops(&phys_enc->ops);
>   	phys_enc->intf_mode = INTF_MODE_CMD;
> -	phys_enc->irq[INTR_IDX_UNDERRUN] = phys_enc->hw_intf->cap->intr_underrun;
> -
>   	cmd_enc->stream_sel = 0;
>   
>   	if (!phys_enc->hw_intf) {
> 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 ef69c2f408c3..636a97432d51 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
> @@ -356,6 +356,16 @@ static bool dpu_encoder_phys_vid_needs_single_flush(
>   	return phys_enc->split_role != ENC_ROLE_SOLO;
>   }
>   
> +static void dpu_encoder_phys_vid_atomic_mode_set(
> +		struct dpu_encoder_phys *phys_enc,
> +		struct drm_crtc_state *crtc_state,
> +		struct drm_connector_state *conn_state)
> +{
> +	phys_enc->irq[INTR_IDX_VSYNC] = phys_enc->hw_intf->cap->intr_vsync;
> +
> +	phys_enc->irq[INTR_IDX_UNDERRUN] = phys_enc->hw_intf->cap->intr_underrun;
> +}
> +
>   static int dpu_encoder_phys_vid_control_vblank_irq(
>   		struct dpu_encoder_phys *phys_enc,
>   		bool enable)
> @@ -699,6 +709,7 @@ static int dpu_encoder_phys_vid_get_frame_count(
>   static void dpu_encoder_phys_vid_init_ops(struct dpu_encoder_phys_ops *ops)
>   {
>   	ops->is_master = dpu_encoder_phys_vid_is_master;
> +	ops->atomic_mode_set = dpu_encoder_phys_vid_atomic_mode_set;
>   	ops->enable = dpu_encoder_phys_vid_enable;
>   	ops->disable = dpu_encoder_phys_vid_disable;
>   	ops->control_vblank_irq = dpu_encoder_phys_vid_control_vblank_irq;
> @@ -737,8 +748,6 @@ struct dpu_encoder_phys *dpu_encoder_phys_vid_init(struct drm_device *dev,
>   
>   	dpu_encoder_phys_vid_init_ops(&phys_enc->ops);
>   	phys_enc->intf_mode = INTF_MODE_VIDEO;
> -	phys_enc->irq[INTR_IDX_VSYNC] = phys_enc->hw_intf->cap->intr_vsync;
> -	phys_enc->irq[INTR_IDX_UNDERRUN] = phys_enc->hw_intf->cap->intr_underrun;
>   
>   	DPU_DEBUG_VIDENC(phys_enc, "created intf idx:%d\n", p->hw_intf->idx);
>   
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c
> index d3ea91c1d7d2..356dca5e5ea9 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_wb.c
> @@ -404,6 +404,15 @@ static void dpu_encoder_phys_wb_irq_disable(struct dpu_encoder_phys *phys)
>   		dpu_core_irq_unregister_callback(phys->dpu_kms, phys->irq[INTR_IDX_WB_DONE]);
>   }
>   
> +static void dpu_encoder_phys_wb_atomic_mode_set(
> +		struct dpu_encoder_phys *phys_enc,
> +		struct drm_crtc_state *crtc_state,
> +		struct drm_connector_state *conn_state)
> +{
> +
> +	phys_enc->irq[INTR_IDX_WB_DONE] = phys_enc->hw_wb->caps->intr_wb_done;
> +}
> +
>   static void _dpu_encoder_phys_wb_handle_wbdone_timeout(
>   		struct dpu_encoder_phys *phys_enc)
>   {
> @@ -640,6 +649,7 @@ static bool dpu_encoder_phys_wb_is_valid_for_commit(struct dpu_encoder_phys *phy
>   static void dpu_encoder_phys_wb_init_ops(struct dpu_encoder_phys_ops *ops)
>   {
>   	ops->is_master = dpu_encoder_phys_wb_is_master;
> +	ops->atomic_mode_set = dpu_encoder_phys_wb_atomic_mode_set;
>   	ops->enable = dpu_encoder_phys_wb_enable;
>   	ops->disable = dpu_encoder_phys_wb_disable;
>   	ops->wait_for_commit_done = dpu_encoder_phys_wb_wait_for_commit_done;
> @@ -685,7 +695,6 @@ struct dpu_encoder_phys *dpu_encoder_phys_wb_init(struct drm_device *dev,
>   
>   	dpu_encoder_phys_wb_init_ops(&phys_enc->ops);
>   	phys_enc->intf_mode = INTF_MODE_WB_LINE;
> -	phys_enc->irq[INTR_IDX_WB_DONE] = phys_enc->hw_wb->caps->intr_wb_done;
>   
>   	atomic_set(&wb_enc->wbirq_refcount, 0);
>   
>
> ---
> base-commit: 75fa778d74b786a1608d55d655d42b480a6fa8bd
> change-id: 20240514-dpu-revert-ams-9410abc1ee48
>
> Best regards,