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

[Sakari Ailus <sakari.ailus@linux.intel.com>]

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.

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