On Mon, Jul 02, 2012 at 11:09:26AM +0200, Hans de Goede wrote:
> As discussed in length on the mailinglist, USBDEVFS_URB_BULK_CONTINUATION
> does not work as it should when combined with USBDEVFS_URB_SHORT_NOT_OK
> (which is its intended use) on devices attached to an XHCI controller.
>
> Note that this patch only does not advertise the cap, bulk transfers
> with USBDEVFS_URB_BULK_CONTINUATION will still be accepted. Returning
> -EINVAL for them would break existing apps, and in most cases the
> troublesome scenario wrt USBDEVFS_URB_SHORT_NOT_OK urbs on XHCI controllers
> will never get hit, so this would break working use cases.
>
> The disadvantage of not returning -EINVAL is that cases were it is causing
> real trouble may go undetected / the cause of the trouble may be unclear,
> but this is the best we can do.
>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Acked-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
Let me know if Greg wants this patch to come through my queue or not.
> ---
> drivers/usb/core/devio.c | 3 ++-
> drivers/usb/host/xhci.c | 2 ++
> include/linux/usb.h | 5 +++++
> 3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> index 3807ea6..b3a5e2b 100644
> --- a/drivers/usb/core/devio.c
> +++ b/drivers/usb/core/devio.c
> @@ -1823,7 +1823,8 @@ static int proc_get_capabilities(struct dev_state *ps, void __user *arg)
> __u32 caps;
>
> caps = USBDEVFS_CAP_ZERO_PACKET | USBDEVFS_CAP_NO_PACKET_SIZE_LIM;
> - caps |= USBDEVFS_CAP_BULK_CONTINUATION;
> + if (!ps->dev->bus->no_stop_on_short)
> + caps |= USBDEVFS_CAP_BULK_CONTINUATION;
>
> if (put_user(caps, (__u32 __user *)arg))
> return -EFAULT;
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 36641a7..bde855f 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -3974,6 +3974,8 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
>
> /* Accept arbitrarily long scatter-gather lists */
> hcd->self.sg_tablesize = ~0;
> + /* XHCI controllers don't stop the ep queue on short packets :| */
> + hcd->self.no_stop_on_short = 1;
>
> if (usb_hcd_is_primary_hcd(hcd)) {
> xhci = kzalloc(sizeof(struct xhci_hcd), GFP_KERNEL);
> diff --git a/include/linux/usb.h b/include/linux/usb.h
> index 73b68d1..748ca86 100644
> --- a/include/linux/usb.h
> +++ b/include/linux/usb.h
> @@ -331,6 +331,11 @@ struct usb_bus {
> u8 otg_port; /* 0, or number of OTG/HNP port */
> unsigned is_b_host:1; /* true during some HNP roleswitches */
> unsigned b_hnp_enable:1; /* OTG: did A-Host enable HNP? */
> + unsigned no_stop_on_short:1; /*
> + * Quirk: some controllers don't stop
> + * the ep queue on a short transfer
> + * with the URB_SHORT_NOT_OK flag set.
> + */
> unsigned sg_tablesize; /* 0 or largest number of sg list entries */
>
> int devnum_next; /* Next open device number in
> --
> 1.7.10.4
>
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