On 7/23/22 2:04 AM, Bart Van Assche wrote:
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@xxxxxxxxxxxx wrote:
From: Peter Wang <peter.wang@xxxxxxxxxxxx>
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.
Hi Bart,
No, in drivers/base/core.c:
pm_runtime_get_noresume(dev); => No guarantee device will resume
pm_runtime_barrier(dev); => Only flush pending pm request like
RPM_SUSPENDING/RPM_RESUMING
So, If below two condition is meet.
(1) device is already in RPM_SUSPENDED
(2) device resume is required.
Then driver still need call pm_runtime_get_sync just like
ufshcd_wl_shutdown.
The reason why here can remove pm_runtime_get_sync is because,
(1) ufshcd_wl_shutdown -> pm_runtime_get_sync, will resume hba->dev too.
(2) device resume(turn on clk/power) is not required, even if device is
in RPM_SUSPENDED.
Thanks.
Peter
