diff options
| author | Anton Staaf <robotboy@chromium.org> | 2016-06-13 11:17:27 -0700 |
|---|---|---|
| committer | chrome-bot <chrome-bot@chromium.org> | 2016-06-15 17:54:51 -0700 |
| commit | 3a382417d1de0521472b0f6b9d45553ebd3105d1 (patch) | |
| tree | 2ffe10850d55fc995cb45e517a351f0f24036208 /docs | |
| parent | 0201aa1620e89817acf84ff50532b3d4425c63cd (diff) | |
| download | chrome-ec-3a382417d1de0521472b0f6b9d45553ebd3105d1.tar.gz | |
USB Serial: Add README and update CCD docs
The README points the reader back to the docs directory where the
CCD documentation lives. I've added information about the install
script, and about how the raiden module identifies a CCD serial
console.
Signed-off-by: Anton Staaf <robotboy@chromium.org>
BRANCH=None
BUG=None
TEST=make buildall -j
Change-Id: I8714dffcad0b8c30f46529a8f2d670b5d432cda6
Reviewed-on: https://chromium-review.googlesource.com/352787
Commit-Ready: Anton Staaf <robotboy@chromium.org>
Tested-by: Anton Staaf <robotboy@chromium.org>
Reviewed-by: Anton Staaf <robotboy@chromium.org>
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/case_closed_debugging.md | 31 |
1 files changed, 19 insertions, 12 deletions
diff --git a/docs/case_closed_debugging.md b/docs/case_closed_debugging.md index 2bd0d9727b..c3d0eb62ca 100644 --- a/docs/case_closed_debugging.md +++ b/docs/case_closed_debugging.md @@ -29,11 +29,13 @@ ChromiumOS SDK. ### Udev rules file There is a udev rules file, `extra/usb_serial/51-google-serial.rules` that should be installed in `/etc/udev/rules.d/` and udev should be told to reread -its rules. +its rules. This rules file can be installed using the +`extra/usb_serial/install` script. ### Kernel module A trivial Linux kernel module that identifies case closed debug capable USB -interfaces can be found in `extra/usb_serial`. +interfaces can be found in `extra/usb_serial`. This module is also built and +installed using the `extra/usb_serial/install` script. ### ChromiumOS chroot This is really only a requirement for using flashrom. If you only need access @@ -70,16 +72,21 @@ running kernel. It just adds an entry into the `usbserial` module's driver table that causes `usbserial` to recognize any case closed debugging serial console as a simple USB serial device. This addition has already made its way into the upstream kernel (v3.19), so eventually this module can be removed. -The `Makefile` in the `extra/usb_serial` directory will build the kernel module -against the current running kernel, and `insmod raiden.ko` will install it. -If installation fails due to missing dependencies you need to -`modprobe usbserial` first. - -An alternative to using this module is to install `usbserial` with -`modprobe usbserial vendor=<VID> product=<PID>`. The disadvantage of this method -is that it only works for an exact VID:PID match, and the module above does a -more detailed match of the USB descriptors to find interfaces that export the -Google simple serial vendor specific subclass. +The `extra/usb_serial/install` script will build and install the kernel module +as well as install the udev rules file. + +If for some reason you can't or don't want to use the kernel module the install +script provides a --fallback option that will install a udev rules file and +helper script instead that will add each new CCD capable device that is +attached to the host to the list of devices that usbserial will handle. The +disadvantage of this method is that it will generate `/dev/ttyUSB*` entries for +any USB interface on the device that has an IN/OUT pair of bulk endpoints. +This results in extra `/dev/ttyUSB*` entries that should not be used because +they are actually I2C or SPI bridges. + +The raiden module solves this by identifying a CCD serial port by the subclass +and protocol numbers of the USB device interface. This means that there does +not need to be a list of CCD capable device IDs anywhere. Use --- |