On 02/19/2018 04:59 PM, Greg KH wrote:
> On Mon, Feb 19, 2018 at 01:01:07PM +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. Therefore
>> introduce a oc_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.
>> ---
>> drivers/usb/core/hub.c | 4 +++-
>> drivers/usb/core/hub.h | 1 +
>> drivers/usb/core/port.c | 10 ++++++++++
>> 3 files changed, 14 insertions(+), 1 deletion(-)
>
> When you add/remove/modify a sysfs attribute, you always have to
> document in Documentation/ABI/
Ok. Thank you. Seems I missed that, Sorry!
>>
>> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
>> index c5c1f6cf3228..448fba1e1827 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->oc_count++;
>>
>> - dev_dbg(&port_dev->dev, "over-current change\n");
>> + dev_dbg(&port_dev->dev, "over-current change #%u\n",
>> + port_dev->oc_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..b5cf567bf9e2 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 oc_count;
>> };
>>
>> #define to_usb_port(_dev) \
>> diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
>> index 1a01e9ad3804..0bfe410eb8a7 100644
>> --- a/drivers/usb/core/port.c
>> +++ b/drivers/usb/core/port.c
>> @@ -41,6 +41,15 @@ static ssize_t connect_type_show(struct device *dev,
>> }
>> static DEVICE_ATTR_RO(connect_type);
>>
>> +static ssize_t oc_count_show(struct device *dev, struct device_attribute *attr,
>> + char *buf)
>> +{
>> + struct usb_port *port_dev = to_usb_port(dev);
>> +
>> + return sprintf(buf, "%u\n", port_dev->oc_count);
>> +}
>> +static DEVICE_ATTR_RO(oc_count);
>
> I don't see what userspace can do with this number, as there's not much
> it can do with it.
I've answered this question to Felipe already:
On 02/19/2018 03:12 PM, Richard Leitner wrote:
> 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 use reduce the max power always.
>
> With this patch I want to give the user-space application the possibility to
> react adequately to such over-current situations.
>
> I hope this explains my motivation for this patch in a comprehensible way.
I'm of course always open for a better/cleaner/safer way of doing this ;-)
Thank you!
regards;Richard.L
--
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
