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Date: Fri, 11 Dec 2020 09:09:18 +0800 From: Can Guo <cang@...eaurora.org> To: Bean Huo <huobean@...il.com> Cc: asutoshd@...eaurora.org, nguyenb@...eaurora.org, hongwus@...eaurora.org, rnayak@...eaurora.org, linux-scsi@...r.kernel.org, kernel-team@...roid.com, saravanak@...gle.com, salyzyn@...gle.com, 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>, Bart Van Assche <bvanassche@....org>, Satya Tangirala <satyat@...gle.com>, open list <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 1/2] scsi: ufs: Protect some contexts from unexpected clock scaling On 2020-12-11 01:34, Bean Huo wrote: > Hi Can > > On Wed, 2020-12-09 at 05:35 -0800, Can Guo wrote: >> >> >> @@ -1160,6 +1166,7 @@ static void >> ufshcd_clock_scaling_unprepare(struct ufs_hba *hba) >> { >> up_write(&hba->clk_scaling_lock); >> ufshcd_scsi_unblock_requests(hba); >> + ufshcd_release(hba); >> } >> >> /** >> @@ -1175,12 +1182,9 @@ static int ufshcd_devfreq_scale(struct ufs_hba >> *hba, bool scale_up) >> { >> int ret = 0; >> >> - /* let's not get into low power until clock scaling is >> completed */ >> - ufshcd_hold(hba, false); >> - >> ret = ufshcd_clock_scaling_prepare(hba); >> if (ret) >> - goto out; >> + return ret; >> >> /* scale down the gear before scaling down clocks */ >> if (!scale_up) { >> @@ -1212,8 +1216,6 @@ static int ufshcd_devfreq_scale(struct ufs_hba >> *hba, bool scale_up) >> >> out_unprepare: >> ufshcd_clock_scaling_unprepare(hba); >> -out: >> - ufshcd_release(hba); >> return ret; >> } > > I didn't understand why moving ufshcd_hold/ufshcd_release into > ufshcd_clock_scaling_prepare()/ufshcd_clock_scaling_unprepare(). > Say you change devfreq's governor to performance after UFS host has entered runtime suspend. governor_store devfreq_performance_handler update_devfreq devfreq_set_target ufshcd_devfreq_target ufshcd_devfreq_scale When ufshcd_devfreq_scale() calls ufshcd_hold() when host is already runtime suspended, guess what, NoC issues. So clk_scaling.is_allowed should be checked first. Regards, Can Guo. > >> >> @@ -1294,15 +1296,8 @@ static int ufshcd_devfreq_target(struct device >> *dev, >> } >> spin_unlock_irqrestore(hba->host->host_lock, irq_flags); >> >> - pm_runtime_get_noresume(hba->dev); >> - if (!pm_runtime_active(hba->dev)) { >> - pm_runtime_put_noidle(hba->dev); >> - ret = -EAGAIN; >> - goto out; >> - } >> start = ktime_get(); >> ret = ufshcd_devfreq_scale(hba, scale_up); >> - pm_runtime_put(hba->dev); >> > > which branch are you working on? I didn't see this part codes in the > branch 5.11/scsi-queue and 5.11/scsi-staging. > > Bean
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