Re: [PATCH 3/3] scsi: ufs: Let devices remain runtime suspended during system suspend

[Adrian Hunter <adrian.hunter@intel.com>]

On 2/09/21 8:07 pm, Asutosh Das (asd) wrote:
> On 9/2/2021 3:18 AM, Adrian Hunter wrote:
>> If the UFS Device WLUN is runtime suspended and is in the same power
>> mode, link state and b_rpm_dev_flush_capable (BKOP or WB buffer flush etc)
>> state, then it can remain runtime suspended instead of being runtime
>> resumed and then system suspended.
>>
>> The following patches have cleared the way for that to happen:
>>    scsi: ufs: Fix runtime PM dependencies getting broken
>>    scsi: ufs: Fix error handler clear ua deadlock
>>
>> So amend the logic accordingly.
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
>> ---
>>   drivers/scsi/ufs/ufshcd.c | 45 ++++++++++++++++++++++++++++-----------
>>   drivers/scsi/ufs/ufshcd.h | 11 +++++++++-
>>   2 files changed, 43 insertions(+), 13 deletions(-)
>>
> Hi Adrian,
> Thanks for the change.
> 
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 57ed4b93b949..8e799e47e095 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -9722,13 +9722,29 @@ void ufshcd_resume_complete(struct device *dev)
>>           ufshcd_rpm_put(hba);
>>           hba->complete_put = false;
>>       }
>> -    if (hba->rpmb_complete_put) {
>> -        ufshcd_rpmb_rpm_put(hba);
>> -        hba->rpmb_complete_put = false;
>> -    }
>>   }
>>   EXPORT_SYMBOL_GPL(ufshcd_resume_complete);
>>   +static bool ufshcd_rpm_ok_for_spm(struct ufs_hba *hba)
>> +{
>> +    struct device *dev = &hba->sdev_ufs_device->sdev_gendev;
>> +    enum ufs_dev_pwr_mode dev_pwr_mode;
>> +    enum uic_link_state link_state;
>> +    unsigned long flags;
>> +    bool res;
>> +
> In the current ufshcd_suspend(), there's a ufshcd_vops_suspend().
> That's invoked for different pm_ops independent of the rpm_lvl and spm_lvl.
> I'm not sure if any vendor driver does different things for diff pm_op.
> Perhaps something to check.
> 

Good point.  The logic was that way before "scsi: ufs: core: Enable power
management for wlu" which was first in v5.14, so drivers should expect the
behaviour of this patch.  Checking shows only ufs-hisi does something
different but it sets different rpm_lvl and spm_lvl so wouldn't see any
change.  However I am sending a V2 patch that makes it explicit.