linux-kernel - Re: [PATCH] media: i2c: improve suspend/resume switch performance for GT9769 VCM driver

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Message-ID: <f7fd295b116be6f590350a4733a299676d759f88.camel@mediatek.com>
Date: Sat, 12 Oct 2024 03:34:45 +0000
From: Zhi Mao (毛智) <zhi.mao@...iatek.com>
To: "fshao@...omium.org" <fshao@...omium.org>
CC: "linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"yunkec@...omium.org" <yunkec@...omium.org>, "linux-media@...r.kernel.org"
	<linux-media@...r.kernel.org>,
	Shengnan Wang (王圣男)
	<shengnan.wang@...iatek.com>, "mchehab@...nel.org" <mchehab@...nel.org>,
	Yaya Chang (張雅清) <Yaya.Chang@...iatek.com>,
	"sakari.ailus@...ux.intel.com" <sakari.ailus@...ux.intel.com>,
	"10572168@...com" <10572168@...com>,
	Teddy Chen (陳乾元) <Teddy.Chen@...iatek.com>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>,
	Xiaofeiw Wang (王小飞)
	<ot_xiaofeiw.wang@...iatek.com>, "matthias.bgg@...il.com"
	<matthias.bgg@...il.com>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>
Subject: Re: [PATCH] media: i2c: improve suspend/resume switch performance for
 GT9769 VCM driver

Hi Fei,

Thanks for your review.

On Mon, 2024-09-23 at 17:07 +0800, Fei Shao wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  Hi Zhi,
> 
> On Sat, Aug 31, 2024 at 1:54 PM Zhi Mao <zhi.mao@...iatek.com> wrote:
> 
> Suggestion for the new patch title:
>   media: i2c: dw9768: Use runtime PM autosuspend
> 
> to better describe "what" this patch does to the DW9768 driver, not
> "why".
> Also there's nothing to do with GT9769 in this patch.
> 
> >
> > Chromebook camera AP can switch between video and photo mode,
> > the behavior corresponding to VCM is suspend and resume,
> > it will cause camera preview is not smooth during switching
> operation.
> > We use autosuspend function can fix this issue.
> >
> > Signed-off-by: Zhi Mao <zhi.mao@...iatek.com>
> > ---
> >  drivers/media/i2c/dw9768.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/i2c/dw9768.c
> b/drivers/media/i2c/dw9768.c
> > index 18ef2b35c9aa..7449d29df901 100644
> > --- a/drivers/media/i2c/dw9768.c
> > +++ b/drivers/media/i2c/dw9768.c
> > @@ -374,7 +374,7 @@ static int dw9768_open(struct v4l2_subdev *sd,
> struct v4l2_subdev_fh *fh)
> >
> >  static int dw9768_close(struct v4l2_subdev *sd, struct
> v4l2_subdev_fh *fh)
> >  {
> > -       pm_runtime_put(sd->dev);
> 
> Call pm_runtime_mark_last_busy() to update the power.last_busy field
> for autosuspend to work properly.
> 
> > +       pm_runtime_put_sync_autosuspend(sd->dev);
> 
> Use pm_runtime_put_autosuspend().
> Don't switch to the synchronized variant without reasons.
> 
> >
> >         return 0;
> >  }
> > @@ -490,6 +490,7 @@ static int dw9768_probe(struct i2c_client
> *client)
> >                 goto err_power_off;
> >         }
> >
> > +       pm_runtime_use_autosuspend(dev);
> 
> Add pm_runtime_set_autosuspend_delay() before calling
> pm_runtime_use_autosuspend() to avoid rapid power state bouncing.
> 

I have fixed these suggestion above.
please review patch:

https://lore.kernel.org/all/20241012032805.23545-1-zhi.mao@mediatek.com/


> Regards,
> Fei
> 
> 
> 
> >         pm_runtime_idle(dev);
> >
> >         return 0;
> > --
> > 2.46.0
> >
> >