In the Linux kernel, the following vulnerability has been resolved:usb: dwc3: core: Do core softreset when switch modeAccording to the programming guide, to switch mode for DRD controller,
the driver needs to do the following.To switch from device to host:Reset controller with GCTL.CoreSoftResetSet GCTL.PrtCapDir(host mode)Reset the host with USBCMD.HCRESETThen follow up with the initializing host registers sequenceTo switch from host to device:Reset controller with GCTL.CoreSoftResetSet GCTL.PrtCapDir(device mode)Reset the device with DCTL.CSftRstThen follow up with the initializing registers sequenceCurrently 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@linaro.org/
[2] https://lore.kernel.org/linux-usb/0ba7a6ba-e6a7-9cd4-0695-64fc927e01f1@gmail.com/