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Subject: Re: [PATCH v17 1/2] scsi: ufs: Enable power management for wlun
To:     daejun7.park@samsung.com,
        "cang@codeaurora.org" <cang@codeaurora.org>,
        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>
Cc:     Asutosh Das <asutoshd@codeaurora.org>,
        "linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
        ALIM AKHTAR <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Lee Jones <lee.jones@linaro.org>,
        Bean Huo <beanhuo@micron.com>,
        Kiwoong Kim <kwmad.kim@samsung.com>,
        Wei Yongjun <weiyongjun1@huawei.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Yue Hu <huyue2@yulong.com>,
        Dinghao Liu <dinghao.liu@zju.edu.cn>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Jaegeuk Kim <jaegeuk@kernel.org>,
        Satya Tangirala <satyat@google.com>,
        open list <linux-kernel@vger.kernel.org>
References: <1b3d53dad245a7166f3f67a4c65f3a731e6600b3.1617893198.git.asutoshd@codeaurora.org>
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From:   Adrian Hunter <adrian.hunter@intel.com>
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Date:   Fri, 9 Apr 2021 13:07:13 +0300
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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@codeaurora.org>
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> Signed-off-by: Asutosh Das <asutoshd@codeaurora.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)