On Tue, Feb 20, 2018 at 12:50:33PM +0100, Richard Leitner wrote: > From: Richard Leitner <richard.leitner@xxxxxxxxxxx> > > For some userspace applications information on the number of > over-current conditions at specific USB hub ports is relevant. > > In our case we have a series of USB hardware (using the cp210x driver) > which communicates using a proprietary protocol. These devices sometimes > trigger an over-current situation on some hubs. In case of such an > over-current situation the USB devices offer an interface for reducing > the max used power. As these conditions are quite rare and imply > performance reductions of the device we don't want to reduce the max > power always. > > Therefore give user-space applications the possibility to react > adequately by introducing an over_current_counter in the usb port struct > which is exported via sysfs. > > Signed-off-by: Richard Leitner <richard.leitner@xxxxxxxxxxx> > --- > Tested on an i.MX6DL based board > > Changes v2: > - rename oc_count to over_current_count > - add entry to Documentation/ABI > - add detailled description to commit message > --- > Documentation/ABI/testing/sysfs-bus-usb | 9 +++++++++ > drivers/usb/core/hub.c | 4 +++- > drivers/usb/core/hub.h | 1 + > drivers/usb/core/port.c | 10 ++++++++++ > 4 files changed, 23 insertions(+), 1 deletion(-) > > diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb > index 0bd731cbb50c..27020293c85b 100644 > --- a/Documentation/ABI/testing/sysfs-bus-usb > +++ b/Documentation/ABI/testing/sysfs-bus-usb > @@ -189,6 +189,15 @@ Description: > The file will read "hotplug", "wired" and "not used" if the > information is available, and "unknown" otherwise. > > +What: /sys/bus/usb/devices/.../(hub interface)/portX/over_current_count > +Date: February 2018 > +Contact: Richard Leitner <richard.leitner@xxxxxxxxxxx> > +Description: > + Most hubs are able to detect over-current situations on their > + ports and report them to the kernel. This attribute is to expose > + the number of over-current situation occurred on a specific port > + to user space. This file will contain an unsigned int. "unsigned int" is very vague :) How about "this is a 32bit value"? And what happens when this wraps? Is that allowed? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
