On Mon, Jun 2, 2014 at 6:28 AM, vichy <vichy.kuo@xxxxxxxxx> wrote:
> hi Greg:
>
> 2014-05-31 0:02 GMT+08:00 Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>:
>> On Fri, May 30, 2014 at 11:28:36PM +0800, che-chun Kuo wrote:
>>> We found when we plug in/out usb3.0 device for stress testing, once
>>> usb_get_device_descriptor fail in hub_port_init, we will call hub_port_disable.
>>> Then usb3.0 device may not recover successfully with only hot reset like below function
>>> retval = hub_port_reset(hub, port1, udev, delay, false);
>>>
>>> For covering this error handling, we add warm reset if getting device descriptor fail on usb3.0 devices.
>>
>> Odd linewrapping :(
> since I try to make the explanation more readable, I purposely add
> more blank like.
> sorry for making you confused. ^^
>>
>> Anyway, what makes USB 3 devices so "special" here that they need a
>> reset vs. all other devices?
> in the beginning, I try to add quirk determination in usb driver.
> But get descriptor is the 1st command we get.
> if getting descriptor fail, I have no idea how to add quirk
> determination in usb driver.
>
>>
>> Are you sure your device isn't just broken somehow?
> Yes, your concern is reasonable.
> for accelerating the issue happen, I purposely create diff at the end of mail.
> And I try 5 devices on my hand, 2 of them will not successfully return
> back with only hot reset.
>
> In usb3.0 spec, warm reset will force usb3.0 jump to Rx.detect.
> But hot reset will direct down stream port from to ss.Disabled only
> only if time out happen.
> That is why I add warm reset when get device descriptor fail.
>
> appreciate your help,
>
> diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
> old mode 100644
> new mode 100755
> index f829a1a..ffc5241
> --- a/drivers/usb/core/message.c
> +++ b/drivers/usb/core/message.c
> @@ -18,6 +18,9 @@
>
> #include "usb.h"
>
> +static int try_flag = 0;
> +module_param(try_flag, int, S_IRUGO|S_IWUSR);
> +
> static void cancel_async_set_config(struct usb_device *udev);
>
> struct api_context {
> @@ -912,6 +915,12 @@ int usb_get_device_descriptor(struct usb_device
> *dev, unsigned int size)
> if (!desc)
> return -ENOMEM;
>
> +
> + if ((try_flag <= 3) &&(dev->speed == USB_SPEED_SUPER) &&
> (dev->state == USB_STATE_ADDRESS) && (dev->devpath[0] != '0')){
> + printk(KERN_ERR"purposely let get device descriptor fail\n");
> + try_flag ++;
> + return -2;
> + }
> ret = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, size);
> if (ret >= 0)
> memcpy(&dev->descriptor, desc, size);
What is the status of the hub port prior to the warm reset "lsusb -v"?
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