Hi, On Wed, Mar 06, 2013 at 08:14:34PM +0000, Paul Zimmerman wrote: > > From: Felipe Balbi [mailto:balbi@xxxxxx] > > Sent: Wednesday, March 06, 2013 12:11 PM > > On Wed, Mar 06, 2013 at 07:22:33PM +0000, Paul Zimmerman wrote: > > > > From: Felipe Balbi [mailto:balbi@xxxxxx] > > > > Sent: Wednesday, March 06, 2013 2:36 AM > > > > To: Paul Zimmerman; Kishon Vijay Abraham I; Linux USB Mailing List > > > > Subject: dwc3 PHY autosuspend feature > > > > > > > > Hi Paul, > > > > > > > > Kishon has uncovered a possible 'situation' with dwc3 which we need to > > > > clear up. > > > > > > > > According to your commit 802fde98 (usb: dwc3: support new revisions of > > > > DWC3 core), we don't need to suspend/resume the PHYs at all with any > > > > version > 1.94a, but what we observe is that SUSPHY bits are never set. > > > > > > > > What does that mean ? Would PHY autosuspend be an optional feature by > > > > any chance ? Also, I can't find anywhere in the databook saying that > > > > fiddling with SUSPHY should be avoided due to core IP controlling that > > > > automatically. > > > > > > > > Can you enlighten us ? > > > > > > You still need to set the SusPHY bits, but you only need to do it once. > > > After that, the core will take care of suspending/resuming the PHYs > > > at the right time. You will not see the SusPHY bits changing, though. > > > > > > Actually, for GUSB2PHYCFG.SusPHY you can't just set it once. You > > > need to clear it before any register operation that is marked in the > > > databook with the note "If GUSB2PHYCFG[6] is set to '1', it must be > > > set to '0' prior to issuing this command and may be set to '1' after > > > the command completes". Then when the operation completes > > > you can set it back to 1. > > > > What if I set both to zero during driver probe ? Can I then completely > > forget about them ? > > Yes. But then you will be wasting power by having both PHYs always active. fair enough, but wouldn't the core take care of the PHYs after probe() ? -- balbi
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