linux-kernel - Re: [PATCH v17 1/2] scsi: ufs: Enable power management for wlun

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Date:   Fri, 9 Apr 2021 20:30:00 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     "Asutosh Das (asd)" <asutoshd@...eaurora.org>,
        daejun7.park@...sung.com,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>
Cc:     "linux-arm-msm@...r.kernel.org" <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>,
        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>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Yue Hu <huyue2@...ong.com>,
        Dinghao Liu <dinghao.liu@....edu.cn>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Satya Tangirala <satyat@...gle.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v17 1/2] scsi: ufs: Enable power management for wlun

On 9/04/21 8:15 pm, Asutosh Das (asd) wrote:
> On 4/9/2021 3:07 AM, Adrian Hunter wrote:
>> On 9/04/21 5:27 am, Daejun Park wrote:
>>> Hi Asutosh Das,
>>>
>>>> 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>
>>>> ---
>>>> drivers/scsi/ufs/cdns-pltfrm.c     |   2 +
>>>> drivers/scsi/ufs/tc-dwc-g210-pci.c |   2 +
>>>> drivers/scsi/ufs/ufs-debugfs.c     |   6 +-
>>>> drivers/scsi/ufs/ufs-debugfs.h     |   2 +-
>>>> drivers/scsi/ufs/ufs-exynos.c      |   2 +
>>>> drivers/scsi/ufs/ufs-hisi.c        |   2 +
>>>> drivers/scsi/ufs/ufs-mediatek.c    |  12 +-
>>>> drivers/scsi/ufs/ufs-qcom.c        |   2 +
>>>> drivers/scsi/ufs/ufs_bsg.c         |   6 +-
>>>> drivers/scsi/ufs/ufshcd-pci.c      |  36 +--
>>>> drivers/scsi/ufs/ufshcd.c          | 642 ++++++++++++++++++++++++++-----------
>>>> drivers/scsi/ufs/ufshcd.h          |   6 +
>>>> include/trace/events/ufs.h         |  20 ++
>>>> 13 files changed, 509 insertions(+), 231 deletions(-)
>>>
>>> In this patch, you changed pm_runtime_{get, put}_sync to scsi_autopm_{get, put}_device.
>>> But, scsi_autopm_get_device() calls pm_runtime_put_sync() in case of error
>>> of pm_runtime_get_sync(). So, pm_runtime_put_sync() can be called twice if
>>> scsi_autopm_get_device has error.
>>
>> Also it might be tidy to make wrappers e.g.
>>
>> static inline int ufshcd_rpm_get_sync(struct ufs_hba *hba)
>> {
>>      return pm_runtime_get_sync(&hba->sdev_ufs_device->sdev_gendev);
>> }
>>     static inline int ufshcd_rpm_put(struct ufs_hba *hba)
>> {
>>      return pm_runtime_put(&hba->sdev_ufs_device->sdev_gendev);
>> }
>>
>> static inline int ufshcd_rpm_put_sync(struct ufs_hba *hba)
>> {
>>      return pm_runtime_put_sync(&hba->sdev_ufs_device->sdev_gendev);
>> }
>>
>> And also consider matching: e.g.
>>
>>     pm_runtime_put(hba->dev)    to    ufshcd_rpm_put(hba)
>>     pm_runtime_put_sync(hba->dev)    to    ufshcd_rpm_put_sync(hba)
>>
>>
>>
> 
> Ok, I'll push the changes shortly.
> 

I think I will have some more comments, so you could wait if you want.