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SubjectRe: [RFC/RFT] OHCI: Fix for regression in 2.6.37-rc1 since commit 3df7169e7
On Wed, 3 Nov 2010, Larry Finger wrote:

> Following commit 3df7169e73fc1d71a39cffeacc969f6840cdf52b, my logs are spammed
> with messages of the form "hub 2-0:1.0: unable to enumerate USB device on
> port 5".
>
> Experimentation has shown that if the functional state bits of the control
> register are preserved in the fixup, then the messages no longer appear.
>
> Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
> ---
>
> Pali,
>
> Is it possible for you to test this patch to ensure that it does not interfere
> with the fix for the shutdown problem.
>
> Thanks,
>
> Larry
> ---
>
> Index: linux-realtek/drivers/usb/host/pci-quirks.c
> ===================================================================
> --- linux-realtek.orig/drivers/usb/host/pci-quirks.c
> +++ linux-realtek/drivers/usb/host/pci-quirks.c
> @@ -35,6 +35,7 @@
> #define OHCI_INTRENABLE 0x10
> #define OHCI_INTRDISABLE 0x14
> #define OHCI_OCR (1 << 3) /* ownership change request */
> +#define OHCI_CTRL_HCFS (3 << 6) /* functional state */
> #define OHCI_CTRL_RWC (1 << 9) /* remote wakeup connected */
> #define OHCI_CTRL_IR (1 << 8) /* interrupt routing */
> #define OHCI_INTR_OC (1 << 30) /* ownership change */
> @@ -184,7 +185,7 @@ static void __devinit quirk_usb_handoff_
> #ifdef __hppa__
> #define OHCI_CTRL_MASK (OHCI_CTRL_RWC | OHCI_CTRL_IR)
> #else
> -#define OHCI_CTRL_MASK OHCI_CTRL_RWC
> +#define OHCI_CTRL_MASK (OHCI_CTRL_RWC | OHCI_CTRL_HCFS)
>
> if (control & OHCI_CTRL_IR) {
> int wait_time = 500; /* arbitrary; 5 seconds */

This patch is definitely wrong -- it defeats the entire purpose of
rewriting the control register! That write was added _specifically_ to
put the controller into reset, i.e., to change the functional state.

Furthermore, the write does the same thing as ohci_hcd.c does in its
ohci_usb_reset() routine. Regardless, ohci_run() does a complete host
controller reset, which should override anything done in pci-quirks.c.
Perhaps _that_ routine needs some attention.

Alan Stern



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