[Cbe-oss-dev] [PATCH 3/5] usb: PS3 EHCI QH read work-around

[Alan Stern]

On Tue, 15 Nov 2011, Geoff Levand wrote:

> PS3 EHCI HC errata fix 244.  The SCC EHCI HC will not correctly perform QH
> reads that occur near or span a micro-frame boundry.  This is due to a problem
> in the Nak Count Reload Control logic (EHCI Specification 1.0 Section 4.9.1).
> 
> The work-around for this problem is for the HC driver to set I=1 (inactive) for
> QHs with H=1 (list head).
> 
> Signed-off-by: Geoff Levand <geoff at infradead.org>
> ---
>  drivers/usb/host/ehci-hcd.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
> index e43cb5a..4ff0b7e 100644
> --- a/drivers/usb/host/ehci-hcd.c
> +++ b/drivers/usb/host/ehci-hcd.c
> @@ -621,6 +621,7 @@ static int ehci_init(struct usb_hcd *hcd)
>  	hw->hw_next = QH_NEXT(ehci, ehci->async->qh_dma);
>  	hw->hw_info1 = cpu_to_hc32(ehci, QH_HEAD);
>  	hw->hw_info1 |= cpu_to_hc32(ehci, (2 << 28));	/* RL = 2 */
> +	hw->hw_info1 |= cpu_to_hc32(ehci, (1 << 7));	/* I = 1 */
>  	hw->hw_token = cpu_to_hc32(ehci, QTD_STS_HALT);
>  	hw->hw_qtd_next = EHCI_LIST_END(ehci);
>  	ehci->async->qh_state = QH_STATE_LINKED;

This should be okay, although the RL stuff isn't needed.  Have you 
tested it on desktop PCs?

Alan Stern