On 4/16/2021 3:47 AM, Felipe Balbi wrote: > > Hi, > > Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> writes: > >> From: Yu Chen <chenyu56@xxxxxxxxxx> >> From: John Stultz <john.stultz@xxxxxxxxxx> >> >> According to the programming guide, to switch mode for DRD controller, >> the driver needs to do the following. >> >> To switch from device to host: >> 1. Reset controller with GCTL.CoreSoftReset >> 2. Set GCTL.PrtCapDir(host mode) >> 3. Reset the host with USBCMD.HCRESET >> 4. Then follow up with the initializing host registers sequence >> >> To switch from host to device: >> 1. Reset controller with GCTL.CoreSoftReset >> 2. Set GCTL.PrtCapDir(device mode) >> 3. Reset the device with DCTL.CSftRst >> 4. Then follow up with the initializing registers sequence >> >> Currently we're missing step 1) to do GCTL.CoreSoftReset and step 3) of >> switching from host to device. John Stult reported a lockup issue seen >> with HiKey960 platform without these steps[1]. Similar issue is observed >> with Ferry's testing platform[2]. >> >> So, apply the required steps along with some fixes to Yu Chen's and John >> Stultz's version. The main fixes to their versions are the missing wait >> for clocks synchronization before clearing GCTL.CoreSoftReset and only >> apply DCTL.CSftRst when switching from host to device. >> >> [1] https://lore.kernel.org/linux-usb/20210108015115.27920-1-john.stultz@xxxxxxxxxx/ >> [2] https://lore.kernel.org/linux-usb/0ba7a6ba-e6a7-9cd4-0695-64fc927e01f1@xxxxxxxxx/ >> >> Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> >> Cc: Ferry Toth <fntoth@xxxxxxxxx> >> Cc: Wesley Cheng <wcheng@xxxxxxxxxxxxxx> >> Cc: <stable@xxxxxxxxxxxxxxx> >> Fixes: 41ce1456e1db ("usb: dwc3: core: make dwc3_set_mode() work properly") >> Signed-off-by: Yu Chen <chenyu56@xxxxxxxxxx> >> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> >> Signed-off-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> > > I still have concerns about the soft reset, but I won't block you guys > from fixing Hikey's problem :-) > > The only thing I would like to confirm is that this has been verified > with hundreds of swaps happening as quickly as possible. DWC3 should > still be functional after several hundred swaps. > > Can someone confirm this is the case? (I'm assuming this can be > scripted) > Hi Thinh/Felipe, Thanks Thinh for this change. Will verify this on our platform as well with a mode switch loop over the weekend. Thanks Wesley Cheng -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
