On Wednesday 04 February 2009, Sergei Shtylyov wrote:
> Remove wrongly applied upper limit on the interrupt transfer interval for the
> low speed devices (not much of an error per se, according to the USB specs)...
>
> Signed-off-by: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
Acked-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
OK for 2.6.29-rc, though as "not much of an error"
I wouldn't push for it.
> ---
> The patch is against the recent Linus' kernel.
>
> drivers/usb/musb/musb_host.c | 18 ++++++++++--------
> 1 files changed, 10 insertions(+), 8 deletions(-)
>
> Index: linux-2.6/drivers/usb/musb/musb_host.c
> ===================================================================
> --- linux-2.6.orig/drivers/usb/musb/musb_host.c
> +++ linux-2.6/drivers/usb/musb/musb_host.c
> @@ -1857,19 +1857,21 @@ static int musb_urb_enqueue(
> }
> qh->type_reg = type_reg;
>
> - /* precompute rxinterval/txinterval register */
> - interval = min((u8)16, epd->bInterval); /* log encoding */
> + /* Precompute RXINTERVAL/TXINTERVAL register */
> switch (qh->type) {
> case USB_ENDPOINT_XFER_INT:
> - /* fullspeed uses linear encoding */
> - if (USB_SPEED_FULL == urb->dev->speed) {
> - interval = epd->bInterval;
> - if (!interval)
> - interval = 1;
> + /*
> + * Full/low speeds use the linear encoding,
> + * high speed uses the logarithmic encoding.
> + */
> + if (urb->dev->speed <= USB_SPEED_FULL) {
> + interval = max_t(u8, epd->bInterval, 1);
> + break;
> }
> /* FALLTHROUGH */
> case USB_ENDPOINT_XFER_ISOC:
> - /* iso always uses log encoding */
> + /* ISO always uses logarithmic encoding */
> + interval = min_t(u8, epd->bInterval, 16);
> break;
> default:
> /* REVISIT we actually want to use NAK limits, hinting to the
>
>
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