Re: [PATCH 3/8] drm/msm: dpu: Remove vblank_callback from encoder

[Jeykumar Sankaran <jsanka-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>]

On 2018-11-13 12:52, Sean Paul wrote:
> From: Sean Paul <seanpaul@chromium.org>
> 
> The indirection of registering a callback and opaque pointer isn't real
> useful when there's only one callsite. So instead of having the
> vblank_cb registration, just give encoder a crtc and let it directly
> call the vblank handler.
> 
> In a later patch, we'll make use of this further.
> 
> Signed-off-by: Sean Paul <seanpaul@chromium.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c    |  8 +++----
>  drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h    |  6 +++++
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 25 +++++++++++----------
>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h | 10 ++++-----
>  4 files changed, 26 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> index adda0aa0cbaa..38119b4d4a80 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> @@ -291,9 +291,8 @@ enum dpu_intf_mode dpu_crtc_get_intf_mode(struct
> drm_crtc *crtc)
>  	return INTF_MODE_NONE;
>  }
> 
> -static void dpu_crtc_vblank_cb(void *data)
> +void dpu_crtc_vblank_callback(struct drm_crtc *crtc)
>  {
> -	struct drm_crtc *crtc = (struct drm_crtc *)data;
>  	struct dpu_crtc *dpu_crtc = to_dpu_crtc(crtc);

Since we are calling into a locally stored CRTC and not tracking 
disable. Should
we check for crtc->enable before processing the callback?

I see vblank_on/off cant be called when CRTC is disabled with the rest
of the patches in the series. But this callback is triggered by IRQ's
context.

> 
>  	/* keep statistics on vblank callback - with auto reset via
> debugfs */
> @@ -779,8 +778,7 @@ static void _dpu_crtc_vblank_enable_no_lock(
>  						     DRMID(enc), enable,
>  						     dpu_crtc);
> 
> -			dpu_encoder_register_vblank_callback(enc,
> -					dpu_crtc_vblank_cb, (void *)crtc);
> +			dpu_encoder_assign_crtc(enc, crtc);
>  		}
>  	} else {
>  		list_for_each_entry(enc, &dev->mode_config.encoder_list,
> head) {
> @@ -791,7 +789,7 @@ static void _dpu_crtc_vblank_enable_no_lock(
>  						     DRMID(enc), enable,
>  						     dpu_crtc);
> 
> -			dpu_encoder_register_vblank_callback(enc, NULL,
> NULL);
> +			dpu_encoder_assign_crtc(enc, NULL);
>  		}
>  	}
>  }
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
> b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
> index 93d21a61a040..54595cc29be5 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
> @@ -270,6 +270,12 @@ static inline int dpu_crtc_frame_pending(struct
> drm_crtc *crtc)
>   */
>  int dpu_crtc_vblank(struct drm_crtc *crtc, bool en);
> 
> +/**
> + * dpu_crtc_vblank_callback - called on vblank irq, issues completion
> events
> + * @crtc: Pointer to drm crtc object
> + */
> +void dpu_crtc_vblank_callback(struct drm_crtc *crtc);
> +
>  /**
>   * dpu_crtc_commit_kickoff - trigger kickoff of the commit for this 
> crtc
>   * @crtc: Pointer to drm crtc object
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> index d89ac520f7e6..fd6514f681ae 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> @@ -142,9 +142,11 @@ enum dpu_enc_rc_states {
>   * @intfs_swapped	Whether or not the phys_enc interfaces have been
> swapped
>   *			for partial update right-only cases, such as
> pingpong
>   *			split where virtual pingpong does not generate
> IRQs
> - * @crtc_vblank_cb:	Callback into the upper layer / CRTC for
> - *			notification of the VBLANK
> - * @crtc_vblank_cb_data:	Data from upper layer for VBLANK
> notification
> + * @crtc:		Pointer to the currently assigned crtc. Normally
> you
> + *			would use crtc->state->encoder_mask to determine
> the
> + *			link between encoder/crtc. However in this case we
> need
> + *			to track crtc in the disable() hook which is
> called
> + *			_after_ encoder_mask is cleared.
>   * @crtc_kickoff_cb:		Callback into CRTC that will flush & start
>   *				all CTL paths
>   * @crtc_kickoff_cb_data:	Opaque user data given to crtc_kickoff_cb
> @@ -186,8 +188,7 @@ struct dpu_encoder_virt {
> 
>  	bool intfs_swapped;
> 
> -	void (*crtc_vblank_cb)(void *);
> -	void *crtc_vblank_cb_data;
> +	struct drm_crtc *crtc;
> 
>  	struct dentry *debugfs_root;
>  	struct mutex enc_lock;
> @@ -1241,8 +1242,8 @@ static void dpu_encoder_vblank_callback(struct
> drm_encoder *drm_enc,
>  	dpu_enc = to_dpu_encoder_virt(drm_enc);
> 
>  	spin_lock_irqsave(&dpu_enc->enc_spinlock, lock_flags);
> -	if (dpu_enc->crtc_vblank_cb)
> -		dpu_enc->crtc_vblank_cb(dpu_enc->crtc_vblank_cb_data);
> +	if (dpu_enc->crtc)
> +		dpu_crtc_vblank_callback(dpu_enc->crtc);
>  	spin_unlock_irqrestore(&dpu_enc->enc_spinlock, lock_flags);
> 
>  	atomic_inc(&phy_enc->vsync_cnt);
> @@ -1262,15 +1263,14 @@ static void 
> dpu_encoder_underrun_callback(struct
> drm_encoder *drm_enc,
>  	DPU_ATRACE_END("encoder_underrun_callback");
>  }
> 
> -void dpu_encoder_register_vblank_callback(struct drm_encoder *drm_enc,
> -		void (*vbl_cb)(void *), void *vbl_data)
> +void dpu_encoder_assign_crtc(struct drm_encoder *drm_enc, struct 
> drm_crtc
> *crtc)
>  {
>  	struct dpu_encoder_virt *dpu_enc = to_dpu_encoder_virt(drm_enc);
>  	unsigned long lock_flags;
>  	bool enable;
>  	int i;
> 
> -	enable = vbl_cb ? true : false;
> +	enable = crtc ? true : false;
> 
>  	if (!drm_enc) {
>  		DPU_ERROR("invalid encoder\n");
> @@ -1279,8 +1279,9 @@ void dpu_encoder_register_vblank_callback(struct
> drm_encoder *drm_enc,
>  	trace_dpu_enc_vblank_cb(DRMID(drm_enc), enable);
> 
>  	spin_lock_irqsave(&dpu_enc->enc_spinlock, lock_flags);
> -	dpu_enc->crtc_vblank_cb = vbl_cb;
> -	dpu_enc->crtc_vblank_cb_data = vbl_data;
> +	/* crtc should always be cleared before re-assigning */
> +	WARN_ON(crtc && dpu_enc->crtc);
> +	dpu_enc->crtc = crtc;
>  	spin_unlock_irqrestore(&dpu_enc->enc_spinlock, lock_flags);
> 
>  	for (i = 0; i < dpu_enc->num_phys_encs; i++) {
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> index aa4f135218fa..be1d80867834 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h
> @@ -55,14 +55,12 @@ void dpu_encoder_get_hw_resources(struct 
> drm_encoder
> *encoder,
>  				  struct dpu_encoder_hw_resources
> *hw_res);
> 
>  /**
> - * dpu_encoder_register_vblank_callback - provide callback to encoder
> that
> - *	will be called on the next vblank.
> + * dpu_encoder_assign_crtc - Link the encoder to the crtc it's 
> assigned
> to
>   * @encoder:	encoder pointer
> - * @cb:		callback pointer, provide NULL to deregister and
> disable IRQs
> - * @data:	user data provided to callback
> + * @crtc:	crtc pointer
>   */
> -void dpu_encoder_register_vblank_callback(struct drm_encoder *encoder,
> -		void (*cb)(void *), void *data);
> +void dpu_encoder_assign_crtc(struct drm_encoder *encoder,
> +			     struct drm_crtc *crtc);
> 
>  /**
>   * dpu_encoder_register_frame_event_callback - provide callback to
> encoder that

-- 
Jeykumar S
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