linux-kernel - Re: [PATCH v15 1/2] scsi: ufs: Enable power management for wlun

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Date:   Wed, 7 Apr 2021 13:21:25 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Asutosh Das <asutoshd@...eaurora.org>, cang@...eaurora.org,
        martin.petersen@...cle.com, linux-scsi@...r.kernel.org
Cc:     linux-arm-msm@...r.kernel.org,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Pedro Sousa <pedrom.sousa@...opsys.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Bean Huo <beanhuo@...ron.com>,
        Kiwoong Kim <kwmad.kim@...sung.com>,
        Wei Yongjun <weiyongjun1@...wei.com>,
        Yue Hu <huyue2@...ong.com>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Dinghao Liu <dinghao.liu@....edu.cn>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Satya Tangirala <satyat@...gle.com>,
        open list <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/SAMSUNG S3C, S5P AND EXYNOS ARM ARCHITECTURES" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/SAMSUNG S3C, S5P AND EXYNOS ARM ARCHITECTURES" 
        <linux-samsung-soc@...r.kernel.org>,
        "moderated list:UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER..." 
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v15 1/2] scsi: ufs: Enable power management for wlun

On 6/04/21 8:52 pm, Asutosh Das wrote:
> During runtime-suspend of ufs host, the scsi devices are
> already suspended and so are the queues associated with them.
> But the ufs host sends SSU (START_STOP_UNIT) to wlun
> during its runtime-suspend.
> During the process blk_queue_enter checks if the queue is not in
> suspended state. If so, it waits for the queue to resume, and never
> comes out of it.
> The commit
> (d55d15a33: scsi: block: Do not accept any requests while suspended)
> adds the check if the queue is in suspended state in blk_queue_enter().
> 
> Call trace:
>  __switch_to+0x174/0x2c4
>  __schedule+0x478/0x764
>  schedule+0x9c/0xe0
>  blk_queue_enter+0x158/0x228
>  blk_mq_alloc_request+0x40/0xa4
>  blk_get_request+0x2c/0x70
>  __scsi_execute+0x60/0x1c4
>  ufshcd_set_dev_pwr_mode+0x124/0x1e4
>  ufshcd_suspend+0x208/0x83c
>  ufshcd_runtime_suspend+0x40/0x154
>  ufshcd_pltfrm_runtime_suspend+0x14/0x20
>  pm_generic_runtime_suspend+0x28/0x3c
>  __rpm_callback+0x80/0x2a4
>  rpm_suspend+0x308/0x614
>  rpm_idle+0x158/0x228
>  pm_runtime_work+0x84/0xac
>  process_one_work+0x1f0/0x470
>  worker_thread+0x26c/0x4c8
>  kthread+0x13c/0x320
>  ret_from_fork+0x10/0x18
> 
> Fix this by registering ufs device wlun as a scsi driver and
> registering it for block runtime-pm. Also make this as a
> supplier for all other luns. That way, this device wlun
> suspends after all the consumers and resumes after
> hba resumes.
> 
> Co-developed-by: Can Guo <cang@...eaurora.org>
> Signed-off-by: Can Guo <cang@...eaurora.org>
> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
> ---

v15 seems to be missing the updates to ufs_debugfs_get/put_user_access
that were in v14:


@@ -60,14 +60,14 @@ __acquires(&hba->host_sem)
 		up(&hba->host_sem);
 		return -EBUSY;
 	}
-	pm_runtime_get_sync(hba->dev);
+	scsi_autopm_get_device(hba->sdev_ufs_device);
 	return 0;
 }
 
 static void ufs_debugfs_put_user_access(struct ufs_hba *hba)
 __releases(&hba->host_sem)
 {
-	pm_runtime_put_sync(hba->dev);
+	scsi_autopm_put_device(hba->sdev_ufs_device);
 	up(&hba->host_sem);
 }
 

Also from last comments, the issue below:

<SNIP>

> +#ifdef CONFIG_PM_SLEEP
> +static int ufshcd_wl_poweroff(struct device *dev)
> +{
> +	ufshcd_wl_shutdown(dev);

This turned out to be wrong.  This is a PM op and SCSI has already
quiesced the sdev's.  All that is needed is:

	__ufshcd_wl_suspend(hba, UFS_SHUTDOWN_PM);