Re: [RFC PATCH v2 6/6] drm/rockchip: Add dmc notifier in vop driver

[Chanwoo Choi <cw00.choi@samsung.com>]

Hi,

On 2016년 06월 06일 19:13, Lin Huang wrote:
> when in ddr frequency scaling process, vop can not do
> enable or disable operate, since dcf will base on vop vblank
> time to do frequency scaling and need to get vop irq if there
> have vop enabled. So need register to dmc notifier, and we can
> get the dmc status.

If you want to know when ddr frequency is chanaged,
you can use the DEVFREQ_TRANSITION_NOTIFIER notifier[1] (merged to v4.7-rc1)
which includes the following notification:
- DEVFREQ_PRECHANGE
- DEVFREQ_POSTCHANGE	

[1] "PM / devfreq: Add new DEVFREQ_TRANSITION_NOTIFIER notifier"
- https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0fe3a66410a3ba96679be903f1e287d7a0a264a9

Thanks,
Chanwoo Choi

> 
> Signed-off-by: Lin Huang <hl@rock-chips.com>
> ---
> 
> Changes in v2:
> - None
> 
> Changes in v1:
> - use wait_event instead usleep
> 
>  drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 43 +++++++++++++++++++++++++++--
>  1 file changed, 41 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> index 1c4d5b5..8286048 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> @@ -31,6 +31,8 @@
>  #include <linux/reset.h>
>  #include <linux/delay.h>
>  
> +#include <soc/rockchip/rockchip_dmc.h>
> +
>  #include "rockchip_drm_drv.h"
>  #include "rockchip_drm_gem.h"
>  #include "rockchip_drm_fb.h"
> @@ -116,6 +118,10 @@ struct vop {
>  
>  	const struct vop_data *data;
>  
> +	struct notifier_block dmc_nb;
> +	int dmc_in_process;
> +	wait_queue_head_t	wait_dmc_queue;
> +
>  	uint32_t *regsbak;
>  	void __iomem *regs;
>  
> @@ -426,6 +432,21 @@ static void vop_dsp_hold_valid_irq_disable(struct vop *vop)
>  	spin_unlock_irqrestore(&vop->irq_lock, flags);
>  }
>  
> +static int dmc_notify(struct notifier_block *nb, unsigned long event,
> +		      void *data)
> +{
> +	struct vop *vop = container_of(nb, struct vop, dmc_nb);
> +
> +	if (event == DMCFREQ_ADJUST) {
> +		vop->dmc_in_process = 1;
> +	} else if (event == DMCFREQ_FINISH) {
> +		vop->dmc_in_process = 0;
> +		wake_up(&vop->wait_dmc_queue);
> +	}
> +
> +	return NOTIFY_OK;
> +}
> +
>  static void vop_enable(struct drm_crtc *crtc)
>  {
>  	struct vop *vop = to_vop(crtc);
> @@ -434,6 +455,13 @@ static void vop_enable(struct drm_crtc *crtc)
>  	if (vop->is_enabled)
>  		return;
>  
> +	/*
> +	 * if in dmc scaling frequency process, wait until it finish
> +	 * use 100ms as timeout time.
> +	 */
> +	wait_event_timeout(vop->wait_dmc_queue,
> +			   !vop->dmc_in_process, HZ / 10);
> +
>  	ret = pm_runtime_get_sync(vop->dev);
>  	if (ret < 0) {
>  		dev_err(vop->dev, "failed to get pm runtime: %d\n", ret);
> @@ -485,6 +513,7 @@ static void vop_enable(struct drm_crtc *crtc)
>  	enable_irq(vop->irq);
>  
>  	drm_crtc_vblank_on(crtc);
> +	rockchip_dmc_get(&vop->dmc_nb);
>  
>  	return;
>  
> @@ -505,6 +534,13 @@ static void vop_crtc_disable(struct drm_crtc *crtc)
>  		return;
>  
>  	/*
> +	 * if in dmc scaling frequency process, wait until it finish
> +	 * use 100ms as timeout time.
> +	 */
> +	wait_event_timeout(vop->wait_dmc_queue,
> +			   !vop->dmc_in_process, HZ / 10);
> +
> +	/*
>  	 * We need to make sure that all windows are disabled before we
>  	 * disable that crtc. Otherwise we might try to scan from a destroyed
>  	 * buffer later.
> @@ -517,7 +553,7 @@ static void vop_crtc_disable(struct drm_crtc *crtc)
>  		VOP_WIN_SET(vop, win, enable, 0);
>  		spin_unlock(&vop->reg_lock);
>  	}
> -
> +	rockchip_dmc_put(&vop->dmc_nb);
>  	drm_crtc_vblank_off(crtc);
>  
>  	/*
> @@ -1243,7 +1279,7 @@ static int vop_create_crtc(struct vop *vop)
>  		ret = -ENOENT;
>  		goto err_cleanup_crtc;
>  	}
> -
> +	vop->dmc_nb.notifier_call = dmc_notify;
>  	init_completion(&vop->dsp_hold_completion);
>  	init_completion(&vop->wait_update_complete);
>  	crtc->port = port;
> @@ -1465,6 +1501,9 @@ static int vop_bind(struct device *dev, struct device *master, void *data)
>  	/* IRQ is initially disabled; it gets enabled in power_on */
>  	disable_irq(vop->irq);
>  
> +	init_waitqueue_head(&vop->wait_dmc_queue);
> +	vop->dmc_in_process = 0;
> +
>  	ret = vop_create_crtc(vop);
>  	if (ret)
>  		return ret;
>