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    SubjectRe: ehci-hcd affects hda speed
    On 17-03-08 22:00, David Brownell wrote:

    >> On 15-03-08 23:46, Lev A. Melnikovsky wrote:
    >>> changing the bit 5 (EHCI sleep time select: 0=1us 1=10us)
    >>> of register 0x4B seems to resolve my own problem.
    > Note that 10 usec is the value used in the EHCI spec.
    > And yes, waiting only 1 usec between schedule scans is
    > absolutely certain to hammer on the PCI bus quite rudely,
    > preventing other devices from getting Real Work done.
    > Could someone put together an EHCI patch to make sure
    > that bit is set on vt6212 parts? For the VT8235 that
    > register seems to be marked (in an old document someone
    > forwarded to me) as "reserved, do not program"; so this
    > should be specific to vt6212 EHCI. (PCI vendor 0x1106,
    > device 0x3104, revision 0x60 ... the revision being what
    > says "vt6212" vs "vt8235" or "vt8237" etc.

    Just something like this? Completely untested as I've not the hardware
    anymore. Googling for an old lspci, I had a revision 0x63, and Lev has a
    revision 0x65. The VT6212(L) should be 0x60+ it seems.

    The "CC:" should be a "Tested-by:" if that's actually the case.

    But yes, as he also asked, should this be the fix at all?

    commit fb221b24a314069af26db8c9beb6c843efcafa38
    Author: Rene Herman <>
    Date: Tue Mar 18 00:02:16 2008 +0100

    USB: VIA VT6212 10us EHCI sleep time select

    The VIA VT6212 uses a 1us EHCI sleep time by default which
    hammers the PCI bus bad. Use the 10us spec value instead
    as suggested by Lev A. Melnikovsky.

    CC: Lev A. Melnikovsky <>
    Signed-off-by: Rene Herman <>

    diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
    index 3ba0166..35a6ccb 100644
    --- a/drivers/usb/host/ehci-pci.c
    +++ b/drivers/usb/host/ehci-pci.c
    @@ -152,6 +152,15 @@ static int ehci_pci_setup(struct usb_hcd *hcd)
    + case PCI_VENDOR_ID_VIA:
    + if (pdev->device == 0x3104 && pdev->revision >= 0x60) {
    + u8 tmp;
    + /* VT6212: EHCI sleep time 10us (default 1) */
    + pci_read_config_byte(pdev, 0x4b, &tmp);
    + pci_write_config_byte(pdev, 0x4b, tmp | 0x20);
    + }
    + break;

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