On 2019-12-31 12:22, Stanley Chu wrote:
Hi Can,
Hi Stanley,
I see skipping ufshcd_set_ufs_dev_active() in ufshcd_probe_hba()
if it is called from ufshcd_resume() path is the purpose here.
If so, then ufshcd_set_dev_pwr_mode() would be called, meaning
SSU command will be sent. Why is this SSU command needed to be
sent after a full host reset and restore? Is ufshcd_probe_hba()
not enough to make UFS device fully functional?
After resume (for both runtime resume and system resume), device power
mode shall be back to "Active" to service incoming requests.
I see two cases need device power mode transition during resume flow
1. Device Power Mode = Sleep
2. Device Power Mode = PowerDown
For 1, ufshcd_probe_hba() is not invoked during resume flow,
hba->curr_dev_pwr_mode = SLEEP, thus ufshcd_resume() can invoke
ufshcd_set_dev_pwr_mode() to change device power mode.
For 2, ufshcd_probe_hba() is invoked during resume flow, before this
fix, hba->curr_dev_pwr_mode will be set to ACTIVE (note that only this
flag is set as ACTIVE, but device may be still in PowerDown state if
device power is not fully shutdown or device HW reset is not executed
before resume), in the end, ufshcd_resume() will not invoke
ufshcd_set_dev_pwr_mode() to send SSU command to make device change
back
to Active power mode.
Hi Stanley,
Isn't below change fixing the problem you are saying above?
With it, after ufshcd_link_startup(), UFS device's power mode will
become Active anyways. Do you mean below change is not working properly
and you are removing it?
commit 7caf489b99a42a9017ef3d733912aea8794677e7
Author: subhashj@xxxxxxxxxxxxxx <subhashj@xxxxxxxxxxxxxx>
Date: Wed Nov 23 16:32:20 2016 -0800
scsi: ufs: issue link starup 2 times if device isn't active
If we issue the link startup to the device while its UniPro state is
LinkDown (and device state is sleep/power-down) then link startup
will not move the device state to Active. Device will only move to
active state if the link starup is issued when its UniPro state is
LinkUp. So in this case, we would have to issue the link startup 2
times to make sure that device moves to active state.
Thanks,
Can Guo
But if device is fully reset before resume (not by current mainstream
driver), device can be already in "Active" power mode after power on
again during resume flow. In this case, it is OK to set
hba->curr_dev_pwr_mode as ACTIVE in ufshcd_probe_hba() and SSU command
is not necessary.
Thanks,
Stanley
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