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

From: [email-masked] (Chanwoo Choi)
Date: Thu, 23 Jun 2016 10:19:06 +0900

Hi Lin,

On 2016? 06? 22? 21:25, hl wrote:
> Hi Chanwoo Choi,
> 
> On 2016?06?22? 15:11, Chanwoo Choi wrote:
>> Hi,
>>
>> On 2016? 06? 06? 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.

I check the code when target function is failed.
DEVFREQ_TRANSITION_NOTIFIER notifier[1] is missing the error case as you mentioned.
So, we would add following patches to fix the problem.

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 1d6c803804d5..2bd9d4228b7b 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -268,8 +268,10 @@ int update_devfreq(struct devfreq *devfreq)
        devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
 
        err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
-       if (err)
+       if (err) {
+		freqs.new = cur_freq;
+               devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
                return err;
+       }
 
        freqs.new = freq;
        devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);

Thanks,
Chanwoo Choi

>>
>> Thanks,
>> Chanwoo Choi
>>
>>> Signed-off-by: Lin Huang <[email-masked]>
>>> ---
>>>
>>> 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
>