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

Chanwoo Choi
2016-06-22T07:11:52Z

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;
>