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Date: Thu, 24 Jun 2021 10:34:25 +0800 From: Can Guo <cang@...eaurora.org> To: Bart Van Assche <bvanassche@....org> Cc: asutoshd@...eaurora.org, nguyenb@...eaurora.org, hongwus@...eaurora.org, ziqichen@...eaurora.org, linux-scsi@...r.kernel.org, kernel-team@...roid.com, Andy Gross <agross@...nel.org>, Bjorn Andersson <bjorn.andersson@...aro.org>, Alim Akhtar <alim.akhtar@...sung.com>, Avri Altman <avri.altman@....com>, "James E.J. Bottomley" <jejb@...ux.ibm.com>, "Martin K. Petersen" <martin.petersen@...cle.com>, Stanley Chu <stanley.chu@...iatek.com>, Bean Huo <beanhuo@...ron.com>, Jaegeuk Kim <jaegeuk@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>, Kiwoong Kim <kwmad.kim@...sung.com>, Satya Tangirala <satyat@...gle.com>, "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>, open list <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v4 01/10] scsi: ufs: Rename flags pm_op_in_progress and is_sys_suspended Typo fixed. On 2021-06-24 10:02, Can Guo wrote: > Hi Bart, > > On 2021-06-24 04:57, Bart Van Assche wrote: >> On 6/23/21 1:05 PM, Bart Van Assche wrote: >>> On 6/23/21 12:35 AM, Can Guo wrote: >>>> Rename pm_op_in_progress and is_sys_suspended to >>>> wlu_pm_op_in_progress and >>>> is_wlu_sys_suspended accordingly. >>> >>> My understanding is that power management operations must be >>> submitted >>> to one particular UFS WLUN (hba->sdev_ufs_device). That makes the >>> "wlu_" >>> part of the new names redundant. In other words, I like the current >>> names better than the new names. Unless if I missed something, >>> consider >>> dropping this patch. >> >> Hi Can, >> >> Reviewing later patches in this series made me realize that there are >> two families of suspend/resume functions. One family of functions >> operates at the platform level while the other family operates at the >> SCSI LUN level. My comments about the suspend/resume functions are as >> follows: >> - It seems redundant to me to have system suspend support at the SCSI >> LUN level (__ufshcd_wl_suspend(hba, UFS_SYSTEM_PM)) and also at the >> platform level. Since the platform device is a parent of the SCSI >> WLUN, can system suspend/resume support be left out from >> ufshcd_wl_pm_ops (or in other words, remove the .freeze and .thaw >> callbacks)? Do we really need two calls from the power management >> subsystem into the UFS driver for every system suspend and every >> system resume? > > Asutosh and Adrian should be the right persons to answer this, since > they've been working together on that huge change for 4 months - > > https://lore.kernel.org/patchwork/patch/1417696/ > > In short, we need a dedicated suspend/resume ops for the UFS device > W-LU because one cannot send requests (not even PM requests) after the > device is runtime suspended - sending SSU cmds in hba suspend/resume > cannot pass through blk_queue_enter() as SSU cmd is sent to the UFS > device W-LU scsi device (by now it is runtime suspended) but not the > hba device. > > Of course we can keep the old way and send the SSU cmd through a > request queue without block layer PM initialized (hba->cmd_queue for > example, by pointing cmd_queue->queuedata to the UFS device W-LU scsi > device), but that would look like a hack. > >> - Because of the device links (device_link_add()), the ufschd_wl_*() >> RPM callbacks are invoked after all LUNs have been suspended. I >> would >> appreciate it if the "ufshcd_wl_" prefix would be changed into >> "ufshcd_lun_" since that would make it more clear that these >> callbacks >> are associated with all LUNs and not only with the WLUN through >> which >> power management commands are submitted. >> > > Sure, we will do that later. > > Thanks, > > Can Guo. > >> Thanks, >> >> Bart.
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