Hello Andy
On Fri, Mar 12, 2021 at 09:33:59PM +0200, Andy Shevchenko wrote:
> Hi!
>
> The fix in the commit
> e5f4ca3fce90 ("usb: dwc3: ulpi: Fix USB2.0 HS/FS/LS PHY suspend regression")
> effectively broke host mode on Intel Edison.
>
> When device in a gadget mode and I attach the USB Mass Storage device
>
> Before: automatically switches to host mode and detects storage and
> everything okay
> After: automatically switches to host mode and that's it.
>
> Revert, as obviously from above, helps.
>
> So, please fix this or I will send revert near to rc5,
As I've explained in the patchlog the commit was required because the
original functionality submitted by Felipe three years ago aside with
questionable fix introduced the suspend mode regression. So an access to
any PHY register over the ULPI interface just disabled "Suspend USB 2.0
HS/FS/LS PHY" mode, which made pointless enabling it in the main part of
the driver and consequently increased the USB bus power consumption. See
the commit e0082698b689 ("usb: dwc3: ulpi: conditionally resume ULPI PHY")
for details. It clears the SusPHY flag and never gets it back. Instead it
was enough to wait a little longer in the ULPI RegAccess busy-loop to let
PHY to get out of the suspend mode and restore the link. So to speak
reverting my patch would mean to get the regression back for all
IP-core versions, which isn't what any of us would want.
What I can suggest to you is to investigate the problem more thorough of why
you having the mass storage device undetected after the mode switching.
At least you need to look at the system log and find out whether it's ULPI
Registers commands timeout to blame. If so then I would take a look at the
PHY hardware manual whether it supports the Low-power mode. In any case
most likely setting "snps,dis_u2_susphy_quirk" property in the DWC USB3 DT
node will help you to work around the problem. Declaring that DT-prop will
effectively disable using the LPM for any mode (Host/gadget/DRD), but will
permit PHY suspension on the system suspend procedure (please see
snps,dis_u2_susphy_quirk implementation for details).
-Sergey
>
> Happy to test any proposed patches! (Maybe Ferry also can help with that)
>
> --
> With Best Regards,
> Andy Shevchenko
