On Tue, Mar 20, 2018 at 11:17:13AM +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>
> ---
> Changes v4:
> - reintroduce forgotten Changelog
> Changes v3:
> - Improve sysfs file description as recommended by greg k-h
> 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 | 10 ++++++++++
> drivers/usb/core/hub.c | 4 +++-
> drivers/usb/core/hub.h | 1 +
> drivers/usb/core/port.c | 10 ++++++++++
> 4 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
> index 0bd731cbb50c..c702c78f24d8 100644
> --- a/Documentation/ABI/testing/sysfs-bus-usb
> +++ b/Documentation/ABI/testing/sysfs-bus-usb
> @@ -189,6 +189,16 @@ 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 32 bit value
> + which wraps to 0 after its maximum is reached.
> +
> What: /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
> Date: November 2015
> Contact: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index c5c1f6cf3228..6f779b518e75 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -5104,8 +5104,10 @@ static void port_event(struct usb_hub *hub, int port1)
>
> if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
> u16 status = 0, unused;
> + port_dev->over_current_count++;
>
> - dev_dbg(&port_dev->dev, "over-current change\n");
> + dev_dbg(&port_dev->dev, "over-current change #%u\n",
> + port_dev->over_current_count);
> usb_clear_port_feature(hdev, port1,
> USB_PORT_FEAT_C_OVER_CURRENT);
> msleep(100); /* Cool down */
> diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
> index 2a700ccc868c..78d7f4dad618 100644
> --- a/drivers/usb/core/hub.h
> +++ b/drivers/usb/core/hub.h
> @@ -100,6 +100,7 @@ struct usb_port {
> unsigned int is_superspeed:1;
> unsigned int usb3_lpm_u1_permit:1;
> unsigned int usb3_lpm_u2_permit:1;
> + unsigned int over_current_count;
This should be 'u32', right? I'll go edit it by hand...
thanks,
greg k-h
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