31b5de5f37
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+huawei@kernel.org> Signed-off-by: Felipe Balbi <balbi@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.