From: "Peter Wang (王信友)" <peter.wang@mediatek.com>
To: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"bvanassche@acm.org" <bvanassche@acm.org>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>
Cc: "Tun-yu Yu (游敦聿)" <Tun-yu.Yu@mediatek.com>,
"Alice Chao (趙珮均)" <Alice.Chao@mediatek.com>,
"Eddie Huang (黃智傑)" <eddie.huang@mediatek.com>,
"CC Chou (周志杰)" <cc.chou@mediatek.com>,
"Ed Tsai (蔡宗軒)" <Ed.Tsai@mediatek.com>,
wsd_upstream <wsd_upstream@mediatek.com>,
"Chaotian Jing (井朝天)" <Chaotian.Jing@mediatek.com>,
"Chun-Hung Wu (巫駿宏)" <Chun-hung.Wu@mediatek.com>,
"Yi-fan Peng (彭羿凡)" <Yi-fan.Peng@mediatek.com>,
"Qilin Tan (谭麒麟)" <Qilin.Tan@mediatek.com>,
"linux-mediatek@lists.infradead.org"
<linux-mediatek@lists.infradead.org>,
"Jiajie Hao (郝加节)" <jiajie.hao@mediatek.com>,
"Lin Gui (桂林)" <Lin.Gui@mediatek.com>,
"Naomi Chu (朱詠田)" <Naomi.Chu@mediatek.com>
Subject: Re: [PATCH v1 02/10] ufs: host: mediatek: Correct clock scaling with PM QoS flow
Date: Mon, 22 Sep 2025 08:39:16 +0000 [thread overview]
Message-ID: <c5ffcc850a222b23d1b0ba93c9f28521ff2fedf3.camel@mediatek.com> (raw)
In-Reply-To: <ba381e9a-4cb5-45df-9fe0-3d370a84429d@acm.org>
On Fri, 2025-09-19 at 14:02 -0700, Bart Van Assche wrote:
>
> 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.
Hi Bart,
No, it does not affect power, it affects performance after resume.
After suspend, the UFS core always releases pm_qos, so power is not a
concern.
https://elixir.bootlin.com/linux/v6.16.8/source/drivers/ufs/core/ufshcd.c#L10169
However, after resume, pm_qos is not re-acquired if it was released
during the previous suspend. Therefore, if we set the gear to a high
value for performance, this could be impacted. But in the UFS core,
the gear should be set to low during suspend, so there is no need to
re-acquire pm_qos after resume.
Thansk.
Peter
next prev parent reply other threads:[~2025-09-22 8:39 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-18 10:36 [PATCH v1 00/10] Enhance UFS Mediatek Driver peter.wang
2025-09-18 10:36 ` [PATCH v1 01/10] ufs: host: mediatek: Fix runtime suspend error deadlock peter.wang
2025-09-18 18:27 ` Bart Van Assche
2025-09-19 8:11 ` Peter Wang (王信友)
2025-09-19 20:57 ` Bart Van Assche
2025-09-22 8:37 ` Peter Wang (王信友)
2025-09-22 18:27 ` Bart Van Assche
2025-09-23 5:56 ` Peter Wang (王信友)
2025-09-18 10:36 ` [PATCH v1 02/10] ufs: host: mediatek: Correct clock scaling with PM QoS flow peter.wang
2025-09-18 18:30 ` Bart Van Assche
2025-09-19 8:11 ` Peter Wang (王信友)
2025-09-19 21:02 ` Bart Van Assche
2025-09-22 8:39 ` Peter Wang (王信友) [this message]
2025-09-22 19:21 ` Bart Van Assche
2025-09-23 5:58 ` Peter Wang (王信友)
2025-09-18 10:36 ` [PATCH v1 03/10] ufs: host: mediatek: Adjust clock scaling for PM flow peter.wang
2025-09-18 10:36 ` [PATCH v1 04/10] ufs: host: mediatek: Handle clock scaling for high gear in " peter.wang
2025-09-18 10:36 ` [PATCH v1 05/10] ufs: host: mediatek: Adjust sync length for FASTAUTO mode peter.wang
2025-09-18 19:28 ` Bart Van Assche
2025-09-19 8:12 ` Peter Wang (王信友)
2025-09-18 10:36 ` [PATCH v1 06/10] ufs: host: mediatek: Enable interrupts for MCQ mode peter.wang
2025-09-18 18:34 ` Bart Van Assche
2025-09-19 8:14 ` Peter Wang (王信友)
2025-09-19 21:09 ` Bart Van Assche
2025-09-22 8:41 ` Peter Wang (王信友)
2025-09-22 19:26 ` Bart Van Assche
2025-09-23 5:59 ` Peter Wang (王信友)
2025-09-18 10:36 ` [PATCH v1 07/10] ufs: host: mediatek: Fix shutdown/suspend race condition peter.wang
2025-09-18 18:39 ` Bart Van Assche
2025-09-19 8:15 ` Peter Wang (王信友)
2025-09-19 21:10 ` Bart Van Assche
2025-09-18 10:36 ` [PATCH v1 08/10] ufs: host: mediatek: Remove duplicate function peter.wang
2025-09-18 19:29 ` Bart Van Assche
2025-09-18 10:36 ` [PATCH v1 09/10] ufs: host: mediatek: Add support for new platform with MMIO_OTSD_CTR peter.wang
2025-09-18 10:36 ` [PATCH v1 10/10] ufs: host: mediatek: Support new feature for MT6991 peter.wang
2025-09-18 19:32 ` Bart Van Assche
2025-09-19 8:17 ` Peter Wang (王信友)
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