linux-kernel - Re: [PATCH v1 1/2] scsi: ufs: core: Remove UFS_DEVICE_QUIRK_DELAY_AFTER

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Message-ID: <9706ab36ba82a2522931326e114155c027da5461.camel@mediatek.com>
Date: Fri, 3 Oct 2025 03:10:01 +0000
From: Peter Wang (王信友) <peter.wang@...iatek.com>
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Subject: Re: [PATCH v1 1/2] scsi: ufs: core: Remove
 UFS_DEVICE_QUIRK_DELAY_AFTER_LPM quirk

On Thu, 2025-10-02 at 11:48 -0700, Bao D. Nguyen wrote:
> 
> 
> Hi Peter,
> 
> The current Mediatek platform driver applies this quirk to all ufs
> vendors which is consistent with what we would like to do in the
> Qualcomm platform driver per the vendor's requests.
> 
> I do see that, about 5 years ago, Mediatek merged a patch to keep the
> device vcc always on, probably to workaround some HW issues. Since 

Hi Bao,

Yes, some UFS devices may have issues when turning off VCC.

> this
> is a very old patch and the impact of this change on a broken
> hardware
> is minimal, I would like weight the benefit of cleaning up the ufs
> core
> driver by removing the unnecessary quirk
> UFS_DEVICE_QUIRK_DELAY_AFTER_LPM vs the inconvenience of a 5ms
> (potentially reduce to 2ms) delay impact it may cause on an old
> broken
> HW in the suspend/shutdown path.
> 
> I believe removing the UFS_DEVICE_QUIRK_DELAY_AFTER_LPM quirk in the
> ufs
> core driver as well as all the platform drivers yields positive net
> benefits in this case.
> 
> Thanks, Bao
> 
> 

I think you misunderstood my point.
I am okay with removing this flag, but this patch will cause
devices with VCC always on to unnecessarily wait for the 
delay, resulting in wasted time.

Thanks
Peter