On 5/10/20 11:02 am, Avri Altman wrote: > HI, > >> Drivers that wish to support DeepSleep need to set a new capability flag >> UFSHCD_CAP_DEEPSLEEP and provide a hardware reset via the existing >> ->device_reset() callback. > I would expect that this capability controls sending SSU 4, but it only > controls the sysfs entry?
The sysfs entry is the only way to request DeepSleep. > >> >> It is assumed that UFS devices with wspecversion >= 0x310 support >> DeepSleep. >> >> The UFS specification says to set the IMMED (immediate) flag for the >> Start/Stop Unit command when entering DeepSleep. However some UFS >> devices object to that, which is addressed in a subsequent patch. > After failing to understand what the proper behavior should be with respect > of the IMMED bit, > Although I read the applicable section few time, I gave up and consult our > system guy, > Which is our jedec representative. This is his answer: > "... > In order to avoid uncertainty - the host need to set IMMED bit to '0' (this > is explicitly specified by the standard). > The device responds only after it switches to Pre-DeepSleep state. The host > then switch to H8 and this would trigger the device to transition to > DeepSleep state. > ..." > > So maybe the 2nd patch isn't really needed. Yes I managed to get it the wrong way around! I will drop patch 2 and send V2 of patch 1 in due course.
