On Wednesday 10 June 2009, Alek Du wrote:
> From 5a1db37084a2e0de9bdc645cd7cf9a3d364855da Mon Sep 17 00:00:00 2001
> From: Alek Du <alek.du@xxxxxxxxx>
> Date: Wed, 10 Jun 2009 12:29:57 +0800
> Subject: [PATCH] EHCI: Add no_io_watchdog feature to ehci_hcd
>
> The IO watchdog wakes up system too much (as defined as EHCI_IO_JIFFIES, ~10
> times per second) and actually it won't benefit most no interrupt quirk EHCI
> controllers. Most good EHCI controllers needn't IO watchdog at all.
Right. It happened because VIA controllers had some issues.
A few other early controllers would trigger it now and then,
but I think that was because of now-fixed bugs.
What would be most useful is to turn this flag on for
all non-VIA controllers. Or maybe ... just turn it into a
"needs_io_watchdog" quirk, which is enabled for VIA and
any other controllers that need it.
> This patch
> will let them have a chance to disable it. The Intel Moorestown EHCI controller
> patch will leverage it later.
>
> Signed-off-by: Alek Du <alek.du@xxxxxxxxx>
Acked-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
... though I'd prefer to see the sense of this inverted,
and have the flag enabled only for VIA. That'd be a bit
riskier though.
> ---
> drivers/usb/host/ehci-hcd.c | 2 ++
> drivers/usb/host/ehci.h | 1 +
> 2 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
> index c637207..36cedc9 100644
> --- a/drivers/usb/host/ehci-hcd.c
> +++ b/drivers/usb/host/ehci-hcd.c
> @@ -127,6 +127,8 @@ timer_action(struct ehci_hcd *ehci, enum ehci_timer_action action)
>
> switch (action) {
> case TIMER_IO_WATCHDOG:
> + if (ehci->no_io_watchdog)
> + return;
> t = EHCI_IO_JIFFIES;
> break;
> case TIMER_ASYNC_OFF:
> diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
> index 6cff195..c36d22a 100644
> --- a/drivers/usb/host/ehci.h
> +++ b/drivers/usb/host/ehci.h
> @@ -125,6 +125,7 @@ struct ehci_hcd { /* one per controller */
> unsigned big_endian_mmio:1;
> unsigned big_endian_desc:1;
> unsigned has_amcc_usb23:1;
> + unsigned no_io_watchdog:1;
>
> /* required for usb32 quirk */
> #define OHCI_CTRL_HCFS (3 << 6)
> --
> 1.6.0.4
>
>
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