usb: dwc3: core: Do core softreset when switch mode
authorYu Chen <chenyu56@huawei.com>
Thu, 15 Apr 2021 22:20:30 +0000 (15:20 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 22 Apr 2021 09:56:59 +0000 (11:56 +0200)
commitf88359e1588b85cf0e8209ab7d6620085f3441d9
treedd51f3126222179c397aff8cd02887fc1857cc6f
parent0fdf3c5e06aafdded33c9adab8a6f3bb1fe688f9
usb: dwc3: core: Do core softreset when switch mode

From: John Stultz <john.stultz@linaro.org>

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@linaro.org/
[2] https://lore.kernel.org/linux-usb/0ba7a6ba-e6a7-9cd4-0695-64fc927e01f1@gmail.com/

Fixes: 41ce1456e1db ("usb: dwc3: core: make dwc3_set_mode() work properly")
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Ferry Toth <fntoth@gmail.com>
Cc: Wesley Cheng <wcheng@codeaurora.org>
Cc: <stable@vger.kernel.org>
Tested-by: John Stultz <john.stultz@linaro.org>
Tested-by: Wesley Cheng <wcheng@codeaurora.org>
Signed-off-by: Yu Chen <chenyu56@huawei.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/374440f8dcd4f06c02c2caf4b1efde86774e02d9.1618521663.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/dwc3/core.c
drivers/usb/dwc3/core.h