Re: [PATCH v1 02/10] ufs: host: mediatek: Correct clock scaling with PM QoS flow

[Bart Van Assche <bvanassche@acm.org>]

On 9/19/25 1:11 AM, Peter Wang (王信友) wrote:
> On Thu, 2025-09-18 at 11:30 -0700, Bart Van Assche wrote:
>> On 9/18/25 3:36 AM, peter.wang@mediatek.com wrote:
>> > Correct clock scaling with PM QoS during suspend and resume.
>> > Ensure PM QoS is released during suspend if scaling up and
>> > re-applied after resume. This prevents performance issues
>> > and maintains proper power management.
>> 
>> Is this issue related in any way to the MediaTek UFS host driver? If
>> not, please change this patch into a patch for the UFS core driver
>> such
>> that this issue is fixed for all UFS host drivers at once.
>
> Yes, this is a MediaTek-specific test which disables clock scaling
> and keeps the power mode in high gear.
> So, I don't think this patch should be applied to the ufshcd core.

Hmm ... it is not clear to me why this change is specific to MediaTek
host controllers. Please move the code changes in this patch from the
MediaTek driver into the UFSHCI driver core.

Additionally, why is this change necessary? Suspend and resume should
happen quickly. Does removing CPU latency QoS requests during suspend
and resume really save power? Has the power impact of this patch been
measured?

Thanks,

Bart.