Linux-USB Archive on lore.kernel.org
 help / color / Atom feed
From: Suwan Kim <suwan.kim027@gmail.com>
To: shuah@kernel.org, valentina.manea.m@gmail.com,
	gregkh@linuxfoundation.org
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	Suwan Kim <suwan.kim027@gmail.com>
Subject: [PATCH] usbip: Implement map_urb_for_dma function for vhci to skip dma mapping
Date: Tue, 18 Jun 2019 23:28:17 +0900
Message-ID: <20190618142817.16844-1-suwan.kim027@gmail.com> (raw)

vhci doesn’t do dma for remote device. Actually, the real dma
operation is done by network card driver. So, vhci doesn’t use and
need dma address of transfer buffer of urb.

But hcd provides dma mapping function by defualt in usb_hcd_submit_urb()
and it causes unnecessary dma mapping which will be done again at
NIC driver and it wastes CPU cycles. So, implement map_urb_for_dma
function for vhci in order to skip the dma mapping procedure.

Signed-off-by: Suwan Kim <suwan.kim027@gmail.com>
---
 drivers/usb/usbip/vhci_hcd.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
index 667d9c0ec905..9df4d9e36788 100644
--- a/drivers/usb/usbip/vhci_hcd.c
+++ b/drivers/usb/usbip/vhci_hcd.c
@@ -1287,6 +1287,13 @@ static int vhci_free_streams(struct usb_hcd *hcd, struct usb_device *udev,
 	return 0;
 }
 
+static int vhci_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
+			    gfp_t mem_flags)
+{
+	dev_dbg(hcd->self.controller, "vhci does not map urb for dma\n");
+	return 0;
+}
+
 static const struct hc_driver vhci_hc_driver = {
 	.description	= driver_name,
 	.product_desc	= driver_desc,
@@ -1302,6 +1309,7 @@ static const struct hc_driver vhci_hc_driver = {
 	.urb_dequeue	= vhci_urb_dequeue,
 
 	.get_frame_number = vhci_get_frame_number,
+	.map_urb_for_dma = vhci_map_urb_for_dma,
 
 	.hub_status_data = vhci_hub_status,
 	.hub_control    = vhci_hub_control,
-- 
2.20.1


             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-18 14:28 Suwan Kim [this message]
2019-06-18 15:30 ` Alan Stern
2019-06-19  8:16   ` Suwan Kim

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190618142817.16844-1-suwan.kim027@gmail.com \
    --to=suwan.kim027@gmail.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-usb@vger.kernel.org \
    --cc=shuah@kernel.org \
    --cc=valentina.manea.m@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-USB Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-usb/0 linux-usb/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-usb linux-usb/ https://lore.kernel.org/linux-usb \
		linux-usb@vger.kernel.org linux-usb@archiver.kernel.org
	public-inbox-index linux-usb


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-usb


AGPL code for this site: git clone https://public-inbox.org/ public-inbox