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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <fc21ede819d54cd55ecf26239ad1957348e34cfb.camel@mediatek.com>
Date: Sat, 31 Aug 2024 05:59:08 +0000
From: Zhi Mao (毛智) <zhi.mao@...iatek.com>
To: "sakari.ailus@...ux.intel.com" <sakari.ailus@...ux.intel.com>
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>,
	"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>, "matthias.bgg@...il.com"
	<matthias.bgg@...il.com>, "angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>
Subject: Re: [PATCH] media: i2c: improve suspend/resume switch performance for
 GT9769 VCM driver

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
> you have verified the sender or the content.
>  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