At Hikey 970, setting the SPLIT disable at the General
User Register 3 is required.
Without that, the URBs generated by the usbhid driver
return -EPROTO errors. That causes the code at
hid-core.c to call hid_io_error(), which schedules
a reset_work, causing a call to hid_reset().
In turn, the code there will call:
usb_queue_reset_device(usbhid->intf);
The net result is that the input devices won't work, and
will be reset on every 0.5 seconds:
[ 33.122384] hub 1-1:1.0: state 7 ports 4 chg 0000 evt 0002
[ 33.378220] usb 1-1.1: reset low-speed USB device number 3 using
xhci-hcd
[ 33.698394] hub 1-1:1.0: state 7 ports 4 chg 0000 evt 0000
[ 34.882365] hub 1-1:1.0: state 7 ports 4 chg 0000 evt 0002
[ 35.138217] usb 1-1.1: reset low-speed USB device number 3 using
xhci-hcd
[ 35.458617] hub 1-1:1.0: state 7 ports 4 chg 0000 evt 0000
[ 36.642392] hub 1-1:1.0: state 7 ports 4 chg 0000 evt 0002
[ 36.898207] usb 1-1.1: reset low-speed USB device number 3 using
xhci-hcd
[ 37.218598] hub 1-1:1.0: state 7 ports 4 chg 0000 evt 0000
[ 38.402368] hub 1-1:1.0: state 7 ports 4 chg 0000 evt 0002
[ 38.658174] usb 1-1.1: reset low-speed USB device number 3 using
xhci-hcd
[ 38.978594] hub 1-1:1.0: state 7 ports 4 chg 0000 evt 0000
[ 40.162361] hub 1-1:1.0: state 7 ports 4 chg 0000 evt 0002
[ 40.418148] usb 1-1.1: reset low-speed USB device number 3 using
xhci-hcd
...
[ 397.698132] usb 1-1.1: reset low-speed USB device number 3 using
xhci-hcd
Signed-off-by: Mauro Carvalho Chehab <mchehab+hua...@kernel.org>
---
Documentation/devicetree/bindings/usb/dwc3.txt | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt
b/Documentation/devicetree/bindings/usb/dwc3.txt
index d03edf9d3935..1aae2b6160c1 100644
--- a/Documentation/devicetree/bindings/usb/dwc3.txt
+++ b/Documentation/devicetree/bindings/usb/dwc3.txt
@@ -78,6 +78,9 @@ Optional properties:
park mode are disabled.
- snps,dis_metastability_quirk: when set, disable metastability workaround.
CAUTION: use only if you are absolutely sure of it.
+ - snps,dis-split-quirk: when set, change the way URBs are handled by the
+ driver. Needed to avoid -EPROTO errors with usbhid
+ on some devices (Hikey 970).
- snps,is-utmi-l1-suspend: true when DWC3 asserts output signal
utmi_l1_suspend_n, false when asserts utmi_sleep_n
- snps,hird-threshold: HIRD threshold
--
2.26.2
