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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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