linux-kernel - Re: [PATCH V1 2/2] ufs: ufs-qcom: Disable AHIT before SQ tail update to prevent race in MCQ mode

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Message-ID: <bb9c7926-4820-4922-a67d-65a6b1bace9a@acm.org>
Date: Wed, 15 Oct 2025 08:45:18 -0700
From: Bart Van Assche <bvanassche@....org>
To: Palash Kambar <palash.kambar@....qualcomm.com>
Cc: mani@...nel.org, alim.akhtar@...sung.com, avri.altman@....com,
 peter.griffin@...aro.org, krzk@...nel.org, peter.wang@...iatek.com,
 beanhuo@...ron.com, quic_nguyenb@...cinc.com, adrian.hunter@...el.com,
 ebiggers@...nel.org, neil.armstrong@...aro.org,
 James.Bottomley@...senpartnership.com, martin.petersen@...cle.com,
 linux-arm-msm@...r.kernel.org, linux-scsi@...r.kernel.org,
 linux-kernel@...r.kernel.org, quic_cang@...cinc.com,
 quic_nitirawa@...cinc.com
Subject: Re: [PATCH V1 2/2] ufs: ufs-qcom: Disable AHIT before SQ tail update
 to prevent race in MCQ mode

On 10/15/25 7:08 AM, Palash Kambar wrote:
> Since AHIT is a hardware-based power-saving feature, disabling it 
> entirely
> could lead to significant power penalties. Therefore, this patch aims to 
> preserve
> power efficiency while resolving the race condition.
> We have tested this change and observed no noticeable performance 
> degradation.
> Also, adding in RPM callbacks will not solve the power penalty as it 
> autosuspend timer is
> 3 secs in comparision to AHIT timer which is 5ms.

The runtime power management timeout can be modified. Please verify
whether the power consumption with AHIT disabled and the runtime power
management timeout set to 5 ms is acceptable.

Thanks,

Bart.