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

[Zhi Mao (毛智)]

Hi Sakari,

Thanks for your review.


On Wed, 2024-08-28 at 07:51 +0000, Sakari Ailus wrote:
>  	 
> External email : Please do not click links or open attachments until
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>  Hi Zhi,
> 
> Thanks for the patch.
> 
> On Sat, Aug 17, 2024 at 03:34:02PM +0800, Zhi Mao wrote:
> > GT9769 VCM power-on default setting is PD=0,
> > so it is not necessary to set again in dw9768_init function,
> > and it also has no requirement of setting PD=1
> > before power-off in dw9768_release function.
> > For GT9769 VCM, PD mode control will add extra time
> > when switching between suspend and resume.
> > e.g. chrome 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.
> 
> If this is the problem, wouldn't either of these two be a better
> option:
> 
> - keep the file handle open in the user space, to avoid powering off
> the
>   VCM or
> 
> - add autosuspend support to the driver.
We use autosuspend fucntion can fix this issue.
please review: 
https://lore.kernel.org/all/20240831055328.22482-1-zhi.mao@mediatek.com/

> 
> I also wouldn't differentiate driver behaviour between the chips. If
> the
> hardware default really is different (is it, this is rare for
> register-compatible parts), then the driver needs to reprogram it (at
> least
> on the one with a different default).
> 
> -- 
> Kind regards,
> 
> Sakari Ailus