Felipe Balbi wrote:
Hi,
John Stultz john.stultz@linaro.org writes:
On Fri, Apr 16, 2021 at 12:49 PM Thinh Nguyen Thinh.Nguyen@synopsys.com wrote:
John Stultz wrote:
On Fri, Apr 16, 2021 at 3:47 AM Felipe Balbi balbi@kernel.org wrote:
Hi,
Thinh Nguyen Thinh.Nguyen@synopsys.com writes:
From: Yu Chen chenyu56@huawei.com 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:
- Reset controller with GCTL.CoreSoftReset
- Set GCTL.PrtCapDir(host mode)
- Reset the host with USBCMD.HCRESET
- Then follow up with the initializing host registers sequence
To switch from host to device:
- Reset controller with GCTL.CoreSoftReset
- Set GCTL.PrtCapDir(device mode)
- Reset the device with DCTL.CSftRst
- 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://urldefense.com/v3/__https://lore.kernel.org/linux-usb/20210108015115... [2] https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/0ba7a6ba-e6a7-...
Cc: Andy Shevchenko andy.shevchenko@gmail.com Cc: Ferry Toth fntoth@gmail.com Cc: Wesley Cheng wcheng@codeaurora.org Cc: stable@vger.kernel.org Fixes: 41ce1456e1db ("usb: dwc3: core: make dwc3_set_mode() work properly") 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
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)
I unfortunately don't have an easy way to automate the switching right off. But I'll try to hack up the mux switch driver to provide an interface we can script against.
FYI, you can do the following:
- Enable "usb-role-switch" DT property if not already done so
- Add userspace control:
diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c index e2b68bb770d1..b203e3d87291 100644 --- a/drivers/usb/dwc3/drd.c +++ b/drivers/usb/dwc3/drd.c @@ -555,6 +555,7 @@ static int dwc3_setup_role_switch(struct dwc3 *dwc) mode = DWC3_GCTL_PRTCAP_DEVICE; }
dwc3_role_switch.allow_userspace_control = true; dwc3_role_switch.fwnode = dev_fwnode(dwc->dev); dwc3_role_switch.set = dwc3_usb_role_switch_set; dwc3_role_switch.get = dwc3_usb_role_switch_get;
- Write a script to do the following:
# echo host > /sys/class/usb_role/<UDC>/role
and
# echo device > /sys/class/usb_role/<UDC>/role
Thanks so much for this. So I ran both of those commands in a while loop for awhile and didn't see any trouble.
HiKey960 is interesting as well because we have a mux switch, which is sort of an intermediary roll switcher (it gets the role switch signal from the tcpci_rt1711h, tweaks some gpios and then signals the dwc3). So I also did the above tweaks to the mux-switch and had it switching between device/none and validated the onboard hub came up and down along with the dwc3 core.
Everything still looks good here.
Sounds good, happy to see so many platforms supported by Thinh's change. Thanks for doing this work, Thinh :-)
Thanks for the review Felipe :)
Thinh