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

[hl <hl@xxxxxxxxxxxxxx>]

Hi Chanwoo Choi,

On 2016年06月22日 15:11, Chanwoo Choi wrote:

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

Check the code, if the set target fail, it will not send DEVFREQ_POSTCHANGE, but in our case, whether the target
setting sucess or fail, it should send message to vop driver,  tell vop driver dmc have finish frequency setting.

Thanks,
Chanwoo Choi

Signed-off-by: Lin Huang <hl@xxxxxxxxxxxxxx>
---

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;

-- 
Lin Huang

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