| Message ID | 20220719130208.29032-1-peter.wang@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v1] scsi: ufs: correct ufshcd_shutdown flow | expand |
On 7/19/22 06:02, peter.wang@mediatek.com wrote: > From: Peter Wang <peter.wang@mediatek.com> > > After ufshcd_wl_shutdown set device poweroff and link off, > ufshcd_shutdown not turn off regulators/clocks. > Correct the flow to wait ufshcd_wl_shutdown done and turn off > regulators/clocks by polling ufs device/link state 500ms. > Also remove pm_runtime_get_sync because it is unnecessary. Please explain in the patch description why the pm_runtime_get_sync() call is not necessary. > diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c > index c7b337480e3e..1c11af48b584 100644 > --- a/drivers/ufs/core/ufshcd.c > +++ b/drivers/ufs/core/ufshcd.c > @@ -9461,10 +9461,14 @@ EXPORT_SYMBOL(ufshcd_runtime_resume); > */ > int ufshcd_shutdown(struct ufs_hba *hba) > { > - if (ufshcd_is_ufs_dev_poweroff(hba) && ufshcd_is_link_off(hba)) > - goto out; > + ktime_t timeout = ktime_add_ms(ktime_get(), 500); Where does the 500 ms timeout come from? Additionally, given the large timeout, please use jiffies instead of ktime_get(). > - pm_runtime_get_sync(hba->dev); > + /* Wait ufshcd_wl_shutdown clear ufs state, timeout 500 ms */ > + while (!ufshcd_is_ufs_dev_poweroff(hba) || !ufshcd_is_link_off(hba)) { > + if (ktime_after(ktime_get(), timeout)) > + goto out; > + msleep(1); > + } Please explain why this wait loop has been introduced. Thanks, Bart.
On Thu, 2022-07-21 at 12:30 +0800, Peter Wang wrote: > Hi Bart > > On 7/21/22 5:40 AM, Bart Van Assche wrote: > > On 7/19/22 06:02, peter.wang@mediatek.com wrote: > > > From: Peter Wang <peter.wang@mediatek.com> > > > > > > After ufshcd_wl_shutdown set device poweroff and link off, > > > ufshcd_shutdown not turn off regulators/clocks. > > > Correct the flow to wait ufshcd_wl_shutdown done and turn off > > > regulators/clocks by polling ufs device/link state 500ms. > > > Also remove pm_runtime_get_sync because it is unnecessary. > > > > Please explain in the patch description why the > > pm_runtime_get_sync() > > call is not necessary. > > Because shutdown is focus on turn off clock/power, we don't need > turn > on(resume) and turn off, right? > > > > > > diff --git a/drivers/ufs/core/ufshcd.c > > > b/drivers/ufs/core/ufshcd.c > > > index c7b337480e3e..1c11af48b584 100644 > > > --- a/drivers/ufs/core/ufshcd.c > > > +++ b/drivers/ufs/core/ufshcd.c > > > @@ -9461,10 +9461,14 @@ EXPORT_SYMBOL(ufshcd_runtime_resume); > > > */ > > > int ufshcd_shutdown(struct ufs_hba *hba) > > > { > > > - if (ufshcd_is_ufs_dev_poweroff(hba) && > > > ufshcd_is_link_off(hba)) > > > - goto out; > > > + ktime_t timeout = ktime_add_ms(ktime_get(), 500); > > > > Where does the 500 ms timeout come from? > > It is a time to wait device into power off, if the 500 ms is not > suitable, could you suggess a value? > > > > > Additionally, given the large timeout, please use jiffies instead > > of > > ktime_get(). > > Okay, will change next version. > > > > > > - pm_runtime_get_sync(hba->dev); > > > + /* Wait ufshcd_wl_shutdown clear ufs state, timeout 500 ms > > > */ > > > + while (!ufshcd_is_ufs_dev_poweroff(hba) || > > > !ufshcd_is_link_off(hba)) { > > > + if (ktime_after(ktime_get(), timeout)) > > > + goto out; > > > + msleep(1); > > > + } > > > > Please explain why this wait loop has been introduced. > > Both ufshcd_shtdown and ufshcd_wl_shutdown could run concurrently. Is it possible to avoid the dev's shutdown and its parent's shutdown run concurrently ? if cannnot avoid it, then seems the concurrently run case may happen at any device and its parent device! then how do deal with it ? Also, the timeout 500ms may make no sense as the child device may not get the device lock of its parent(it must wait parent's shutdown() return then it can get the device lock). > > if ufshcd_wl_shutdown -> ufshcd_shtdown, clock/power off should ok. > > If ufshcd_shtdown -> ufshcd_wl_shutdown, wait ufshcd_wl_shutdown set > device to power off and turn off clock/power. > > If timeout happen, means device still in active mode, cannot turn > off > clock/power directly. Skip and keep clock/power on in this case. > > > > > > Thanks, > > > > Bart.
On 7/20/22 21:30, Peter Wang wrote: > On 7/21/22 5:40 AM, Bart Van Assche wrote: >> On 7/19/22 06:02, peter.wang@mediatek.com wrote: >>> From: Peter Wang <peter.wang@mediatek.com> >>> Also remove pm_runtime_get_sync because it is unnecessary. >> >> Please explain in the patch description why the pm_runtime_get_sync() >> call is not necessary. > > Because shutdown is focus on turn off clock/power, we don't need turn > on(resume) and turn off, right? Hi Peter, I think that removing the pm_runtime_get_sync() call is safe because the device driver core already performs a runtime resume before the UFS driver shutdown callback function is called. From drivers/base/core.c: /* Don't allow any more runtime suspends */ pm_runtime_get_noresume(dev); pm_runtime_barrier(dev); Thanks, Bart.
On 7/20/22 21:30, Peter Wang wrote: > On 7/21/22 5:40 AM, Bart Van Assche wrote: >> On 7/19/22 06:02, peter.wang@mediatek.com wrote: >>> - pm_runtime_get_sync(hba->dev); >>> + /* Wait ufshcd_wl_shutdown clear ufs state, timeout 500 ms */ >>> + while (!ufshcd_is_ufs_dev_poweroff(hba) || >>> !ufshcd_is_link_off(hba)) { >>> + if (ktime_after(ktime_get(), timeout)) >>> + goto out; >>> + msleep(1); >>> + } >> >> Please explain why this wait loop has been introduced. > > Both ufshcd_shutdown and ufshcd_wl_shutdown could run concurrently. Are you sure of this? In drivers/base/core.c I see a sequential loop in the device_shutdown() function. So how could two shutdown functions run concurrently? Thanks, Bart.
diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c index c7b337480e3e..1c11af48b584 100644 --- a/drivers/ufs/core/ufshcd.c +++ b/drivers/ufs/core/ufshcd.c @@ -9461,10 +9461,14 @@ EXPORT_SYMBOL(ufshcd_runtime_resume); */ int ufshcd_shutdown(struct ufs_hba *hba) { - if (ufshcd_is_ufs_dev_poweroff(hba) && ufshcd_is_link_off(hba)) - goto out; + ktime_t timeout = ktime_add_ms(ktime_get(), 500); - pm_runtime_get_sync(hba->dev); + /* Wait ufshcd_wl_shutdown clear ufs state, timeout 500 ms */ + while (!ufshcd_is_ufs_dev_poweroff(hba) || !ufshcd_is_link_off(hba)) { + if (ktime_after(ktime_get(), timeout)) + goto out; + msleep(1); + } ufshcd_suspend(hba); out: