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

Chanwoo Choi
2016-06-23T01:19:06Z

Hi Lin,

On 2016년 06월 22일 21:25, hl wrote:
> 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.

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 <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;
>>>
>>
>>
>>
>
> --
> Lin Huang
>