Re: [PATCH v1] ufs: core: Remove unnecessary block I/O quiesce for clock scaling

On Thu, Jul 23, 2026 at 01:22:57PM +0000, Peter Wang (王信友) wrote:
> On Thu, 2026-07-23 at 14:39 +0200, Manivannan Sadhasivam wrote:
> > Qcom Host Controllers doesn't support scaling clocks when the traffic
> > is
> > ongoing. So this patch certainly cannot work on our platforms.
> > 
> > If you want to pursue, you should limit this change to MediaTek
> > platforms. But
> > nevertheless, this patch should be reverted as it breaks UFS on all
> > Qcom
> > platforms.
> > 
> > - Mani
> > 
> 
> Hi Mani,
> 
> This patch is based on the JEDEC specification. As all SoCs 
> should follow this spec, I have not applied it solely to 
> MediaTek's platform. However, I think reverting it is okay. 
> I will consider how to revise it later.
> 

What you quoted in the commit message is true for power mode change (gear, lane
etc...), but clock scaling involves scaling up/down the HCI clock inputs as
well, which is not covered by the JEDEC spec and is vendor specific. And this is
where the discrepancy lives.

Qcom UFS HCI also allows power mode change with in-flight traffic, but scaling
the clocks is not supported. I'm not sure about other vendors here.

- Mani

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