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
- Device Power Mode = Sleep
- 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@codeaurora.org subhashj@codeaurora.org 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
Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek