Re: ehci-hcd affects hda speed

[Rene Herman <rene.herman@keyaccess.nl>]

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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?

Rene.

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commit fb221b24a314069af26db8c9beb6c843efcafa38
Author: Rene Herman <rene.herman@gmail.com>
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 <melnikovsky@mail.ru>
    Signed-off-by: Rene Herman <rene.herman@gmail.com>

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)
 			break;
 		}
 		break;
+	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;
 	}
 
 	ehci_reset(ehci);