Re: [PATCH v4 1/4] drm/rockchip: vop: export line flag function

[Sean Paul <seanpaul@chromium.org>]

On Thu, Jul 14, 2016 at 12:15:44PM +0800, Yakir Yang wrote:
> VOP have integrated a hardware counter which indicate the exact display
> line that vop is scanning. And if we're interested in a specific line,
> we can set the line number to vop line_flag register, and then vop would
> generate a line_flag interrupt for it.
> 
> For example eDP PSR function is interested in the vertical blanking
> period, then driver could set the line number to zero.
> 
> This patch have exported a symbol that allow other driver to listen the
> line flag event with given timeout limit:
> -  rockchip_drm_wait_line_flag()
> 
> Signed-off-by: Yakir Yang <ykk@rock-chips.com>
> ---
> Changes in v4:
> - Avoid the weird behavior in rockchip_drm_wait_line_flag(). (Sean)
> - Make line_flag_num_x to an array. (Sean)
> - Remove the unused vop_cfg_done() in vop_line_flag_irq_enable(). (Stephane, reviewed in Google gerrit)
>     [https://chromium-review.googlesource.com/#/c/349084/33/drivers/gpu/drm/rockchip/rockchip_drm_vop.c@466]
> 
> Changes in v3:
> - Export the 'rockchip_drm_wait_line_flag' symbol, and document it.
> - Add 'line_flag_num_0' for RK3288/RK3036
> - Remove the notify for waiting line_flag event (Daniel)
> 
> Changes in v2:
> - Introduce in v2, split VOP line flag changes out
> 
>  drivers/gpu/drm/rockchip/rockchip_drm_drv.h |   3 +
>  drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 118 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/rockchip/rockchip_drm_vop.h |   2 +
>  drivers/gpu/drm/rockchip/rockchip_vop_reg.c |   4 +
>  4 files changed, 127 insertions(+)
> 
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
> index ea39329..239b830 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
> @@ -70,4 +70,7 @@ int rockchip_drm_dma_attach_device(struct drm_device *drm_dev,
>  				   struct device *dev);
>  void rockchip_drm_dma_detach_device(struct drm_device *drm_dev,
>  				    struct device *dev);
> +int rockchip_drm_wait_line_flag(struct drm_crtc *crtc, unsigned int line_num,
> +				unsigned int mstimeout);
> +
>  #endif /* _ROCKCHIP_DRM_DRV_H_ */
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> index c8a62a8..69d32f1 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> @@ -121,6 +121,8 @@ struct vop {
>  	/* protected by dev->event_lock */
>  	struct drm_pending_vblank_event *event;
>  
> +	struct completion line_flag_completion;
> +
>  	const struct vop_data *data;
>  
>  	uint32_t *regsbak;
> @@ -431,6 +433,71 @@ static void vop_dsp_hold_valid_irq_disable(struct vop *vop)
>  	spin_unlock_irqrestore(&vop->irq_lock, flags);
>  }
>  
> +/*
> + * (1) each frame starts at the start of the Vsync pulse which is signaled by
> + *     the "FRAME_SYNC" interrupt.
> + * (2) the active data region of each frame ends at dsp_vact_end
> + * (3) we should program this same number (dsp_vact_end) into dsp_line_frag_num,
> + *      to get "LINE_FLAG" interrupt at the end of the active on screen data.
> + *
> + * VOP_INTR_CTRL0.dsp_line_frag_num = VOP_DSP_VACT_ST_END.dsp_vact_end
> + * Interrupts
> + * LINE_FLAG -------------------------------+
> + * FRAME_SYNC ----+                         |
> + *                |                         |
> + *                v                         v
> + *                | Vsync | Vbp |  Vactive  | Vfp |
> + *                        ^     ^           ^     ^
> + *                        |     |           |     |
> + *                        |     |           |     |
> + * dsp_vs_end ------------+     |           |     |   VOP_DSP_VTOTAL_VS_END
> + * dsp_vact_start --------------+           |     |   VOP_DSP_VACT_ST_END
> + * dsp_vact_end ----------------------------+     |   VOP_DSP_VACT_ST_END
> + * dsp_total -------------------------------------+   VOP_DSP_VTOTAL_VS_END
> + */
> +static bool vop_line_flag_irq_is_enabled(struct vop *vop)
> +{
> +	uint32_t line_flag_irq;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&vop->irq_lock, flags);
> +
> +	line_flag_irq = VOP_INTR_GET_TYPE(vop, enable, LINE_FLAG_INTR);
> +
> +	spin_unlock_irqrestore(&vop->irq_lock, flags);
> +
> +	return !!line_flag_irq;
> +}
> +
> +static void vop_line_flag_irq_enable(struct vop *vop, int line_num)
> +{
> +	unsigned long flags;
> +
> +	if (WARN_ON(!vop->is_enabled))
> +		return;
> +
> +	spin_lock_irqsave(&vop->irq_lock, flags);
> +
> +	VOP_CTRL_SET(vop, line_flag_num[0], line_num);
> +	VOP_INTR_SET_TYPE(vop, enable, LINE_FLAG_INTR, 1);
> +
> +	spin_unlock_irqrestore(&vop->irq_lock, flags);
> +}
> +
> +static void vop_line_flag_irq_disable(struct vop *vop)
> +{
> +	unsigned long flags;
> +
> +	if (WARN_ON(!vop->is_enabled))
> +		return;
> +
> +	spin_lock_irqsave(&vop->irq_lock, flags);
> +
> +	VOP_INTR_SET_TYPE(vop, enable, LINE_FLAG_INTR, 0);
> +
> +	spin_unlock_irqrestore(&vop->irq_lock, flags);
> +}
> +
>  static void vop_enable(struct drm_crtc *crtc)
>  {
>  	struct vop *vop = to_vop(crtc);
> @@ -1157,6 +1224,13 @@ static irqreturn_t vop_isr(int irq, void *data)
>  		ret = IRQ_HANDLED;
>  	}
>  
> +	if (active_irqs & LINE_FLAG_INTR) {
> +		if (!completion_done(&vop->line_flag_completion))
> +			complete(&vop->line_flag_completion);

You still have the completion_done/complete here.

If you just call complete() without checking if it's done, you'll remove the
race I mentioned in my first review.

Sean

> +		active_irqs &= ~LINE_FLAG_INTR;
> +		ret = IRQ_HANDLED;
> +	}
> +
>  	if (active_irqs & FS_INTR) {
>  		drm_crtc_handle_vblank(crtc);
>  		vop_handle_vblank(vop);
> @@ -1255,6 +1329,7 @@ static int vop_create_crtc(struct vop *vop)
>  
>  	init_completion(&vop->dsp_hold_completion);
>  	init_completion(&vop->wait_update_complete);
> +	init_completion(&vop->line_flag_completion);
>  	crtc->port = port;
>  	rockchip_register_crtc_funcs(crtc, &private_crtc_funcs);
>  
> @@ -1411,6 +1486,49 @@ static void vop_win_init(struct vop *vop)
>  	}
>  }
>  
> +/**
> + * rockchip_drm_wait_line_flag - acqiure the give line flag event
> + * @crtc: CRTC to enable line flag
> + * @line_num: interested line number
> + * @mstimeout: millisecond for timeout
> + *
> + * Driver would hold here until the interested line flag interrupt have
> + * happened or timeout to wait.
> + *
> + * Returns:
> + * Zero on success, negative errno on failure.
> + */
> +int rockchip_drm_wait_line_flag(struct drm_crtc *crtc, unsigned int line_num,
> +				unsigned int mstimeout)
> +{
> +	struct vop *vop = to_vop(crtc);
> +	unsigned long jiffies_left;
> +
> +	if (!crtc || !vop->is_enabled)
> +		return -ENODEV;
> +
> +	if (line_num > crtc->mode.vtotal || mstimeout <= 0)
> +		return -EINVAL;
> +
> +	if (vop_line_flag_irq_is_enabled(vop))
> +		return -EBUSY;
> +
> +	reinit_completion(&vop->line_flag_completion);
> +	vop_line_flag_irq_enable(vop, line_num);
> +
> +	jiffies_left = wait_for_completion_timeout(&vop->line_flag_completion,
> +						   msecs_to_jiffies(mstimeout));
> +	vop_line_flag_irq_disable(vop);
> +
> +	if (jiffies_left == 0) {
> +		dev_err(vop->dev, "Timeout waiting for IRQ\n");
> +		return -ETIMEDOUT;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(rockchip_drm_wait_line_flag);
> +
>  static int vop_bind(struct device *dev, struct device *master, void *data)
>  {
>  	struct platform_device *pdev = to_platform_device(dev);
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.h b/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
> index ff4f52e..1dbc526 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
> @@ -61,6 +61,8 @@ struct vop_ctrl {
>  	struct vop_reg hpost_st_end;
>  	struct vop_reg vpost_st_end;
>  
> +	struct vop_reg line_flag_num[2];
> +
>  	struct vop_reg cfg_done;
>  };
>  
> diff --git a/drivers/gpu/drm/rockchip/rockchip_vop_reg.c b/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
> index 6f42e56..eea8427 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
> @@ -122,6 +122,7 @@ static const struct vop_ctrl rk3036_ctrl_data = {
>  	.hact_st_end = VOP_REG(RK3036_DSP_HACT_ST_END, 0x1fff1fff, 0),
>  	.vtotal_pw = VOP_REG(RK3036_DSP_VTOTAL_VS_END, 0x1fff1fff, 0),
>  	.vact_st_end = VOP_REG(RK3036_DSP_VACT_ST_END, 0x1fff1fff, 0),
> +	.line_flag_num[0] = VOP_REG(RK3036_INT_STATUS, 0xfff, 12),
>  	.cfg_done = VOP_REG(RK3036_REG_CFG_DONE, 0x1, 0),
>  };
>  
> @@ -221,6 +222,7 @@ static const struct vop_ctrl rk3288_ctrl_data = {
>  	.vact_st_end = VOP_REG(RK3288_DSP_VACT_ST_END, 0x1fff1fff, 0),
>  	.hpost_st_end = VOP_REG(RK3288_POST_DSP_HACT_INFO, 0x1fff1fff, 0),
>  	.vpost_st_end = VOP_REG(RK3288_POST_DSP_VACT_INFO, 0x1fff1fff, 0),
> +	.line_flag_num[0] = VOP_REG(RK3288_INTR_CTRL0, 0x1fff, 12),
>  	.cfg_done = VOP_REG(RK3288_REG_CFG_DONE, 0x1, 0),
>  };
>  
> @@ -299,6 +301,8 @@ static const struct vop_ctrl rk3399_ctrl_data = {
>  	.vact_st_end = VOP_REG(RK3399_DSP_VACT_ST_END, 0x1fff1fff, 0),
>  	.hpost_st_end = VOP_REG(RK3399_POST_DSP_HACT_INFO, 0x1fff1fff, 0),
>  	.vpost_st_end = VOP_REG(RK3399_POST_DSP_VACT_INFO, 0x1fff1fff, 0),
> +	.line_flag_num[0] = VOP_REG(RK3399_LINE_FLAG, 0xffff, 0),
> +	.line_flag_num[1] = VOP_REG(RK3399_LINE_FLAG, 0xffff, 16),
>  	.cfg_done = VOP_REG_MASK(RK3399_REG_CFG_DONE, 0x1, 0),
>  };
>  
> -- 
> 1.9.1
> 
> 
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