From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Lei Subject: [PATCH v2 1/4] USB: introduce usb_device_no_sg_constraint() helper Date: Mon, 5 Aug 2013 16:47:00 +0800 Message-ID: <1375692423-9497-2-git-send-email-ming.lei@canonical.com> References: <1375692423-9497-1-git-send-email-ming.lei@canonical.com> Cc: Oliver Neukum , Sarah Sharp , netdev@vger.kernel.org, linux-usb@vger.kernel.org, Ming Lei , Alan Stern To: "David S. Miller" , Greg Kroah-Hartman Return-path: Received: from mail-pd0-f171.google.com ([209.85.192.171]:47432 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755330Ab3HEIrk (ORCPT ); Mon, 5 Aug 2013 04:47:40 -0400 In-Reply-To: <1375692423-9497-1-git-send-email-ming.lei@canonical.com> Sender: netdev-owner@vger.kernel.org List-ID: Some host controllers(such as xHCI) can support building packet from discontinuous buffers, so introduce one flag and helper for this kind of host controllers, then the feature can help some applications(such as usbnet) by supporting arbitrary length of sg buffers. Cc: Alan Stern Signed-off-by: Ming Lei --- drivers/usb/core/urb.c | 3 ++- include/linux/usb.h | 11 ++++++++++- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c index e75115a..c77ec78 100644 --- a/drivers/usb/core/urb.c +++ b/drivers/usb/core/urb.c @@ -414,7 +414,8 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags) urb->iso_frame_desc[n].status = -EXDEV; urb->iso_frame_desc[n].actual_length = 0; } - } else if (dev->speed != USB_SPEED_WIRELESS && urb->num_sgs) { + } else if (urb->num_sgs && !urb->dev->bus->no_sg_constraint && + dev->speed != USB_SPEED_WIRELESS) { struct scatterlist *sg; int i; diff --git a/include/linux/usb.h b/include/linux/usb.h index 84f14e2..46cc0f7 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -337,6 +337,7 @@ struct usb_bus { * the ep queue on a short transfer * with the URB_SHORT_NOT_OK flag set. */ + unsigned no_sg_constraint:1; /* no sg constraint */ unsigned sg_tablesize; /* 0 or largest number of sg list entries */ int devnum_next; /* Next open device number in @@ -684,6 +685,14 @@ static inline bool usb_device_supports_ltm(struct usb_device *udev) return udev->bos->ss_cap->bmAttributes & USB_LTM_SUPPORT; } +static inline bool usb_device_no_sg_constraint(struct usb_device *udev) +{ + if (udev && udev->bus && udev->bus->no_sg_constraint) + return true; + else + return false; +} + /*-------------------------------------------------------------------------*/ @@ -1249,7 +1258,7 @@ typedef void (*usb_complete_t)(struct urb *); * transfer_buffer. * @sg: scatter gather buffer list, the buffer size of each element in * the list (except the last) must be divisible by the endpoint's - * max packet size + * max packet size if no_sg_constraint isn't set in 'struct usb_bus' * @num_mapped_sgs: (internal) number of mapped sg entries * @num_sgs: number of entries in the sg list * @transfer_buffer_length: How big is transfer_buffer. The transfer may -- 1.7.9.5