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SubjectRe: [linux-usb-devel] [PATCH] msleep() with hrtimers
On Thu, 9 Aug 2007, Andrew Morton wrote:

> This failed the Vaio test. I guess it triggered a USB bug.
>
> With this patch applied, when I hotplug my wireless mouse, the little LED
> on the mouse comes on for a second or so then goes out and no pointy clicky
> for me.
>
> It says:
>
> [ 152.481522] usb 1-1: new low speed USB device using uhci_hcd and address 2
>
>
> Without this patch applied, I get
>
> [ 195.935445] usb 2-1: new low speed USB device using uhci_hcd and address 2
> [ 196.116183] usb 2-1: configuration #1 chosen from 1 choice
> [ 196.198362] input: Microsoft Microsoft Wireless Optical Mouse 1.00 as /class/input/input7
> [ 196.223724] input: USB HID v1.11 Mouse [Microsoft Microsoft Wireless Optical Mouse 1.00] on usb-0000:00:1d.1-1
> [ 196.224570] usb 2-1: new device found, idVendor=045e, idProduct=00e1
> [ 196.224579] usb 2-1: new device strings: Mfr=1, Product=2, SerialNumber=0
> [ 196.224585] usb 2-1: Product: Microsoft Wireless Optical Mouse 1.00
> [ 196.224590] usb 2-1: Manufacturer: Microsoft
>
> and lots of pointy clickiness.
>
> I would assume that there is some msleep() in USB which is too short, and
> the present wild rounding-up which msleep() does covered up the
> incorrectly-chosen sleep duration.
>
> I'm using HZ=250 (http://userweb.kernel.org/~akpm/config-sony.txt) and it
> could well be that the mouse would fail just by going to HZ=1000, but I
> didn't bother testing that.
>
> Could one of the USB developers please suggest which msleep()(s) I should
> start looking at?

It could be one of the calls in drivers/usb/core/hub.c, however almost
all of them are at least 10 ms already. There's a 0-ms msleep near the
start of hub_port_wait_reset() which might cause problems.

It will be easier to pin down the culprit if you turn on
CONFIG_USB_DEBUG.

Alan Stern

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