Linux-USB Archive on lore.kernel.org
 help / color / Atom feed
From: Suwan Kim <suwan.kim027@gmail.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: shuah@kernel.org, valentina.manea.m@gmail.com,
	stern@rowland.harvard.edu, linux-usb@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 1/2] usbip: Skip DMA mapping and unmapping for urb at vhci
Date: Fri, 23 Aug 2019 07:19:14 +0900
Message-ID: <20190822221912.GA5004@localhost.localdomain> (raw)
In-Reply-To: <20190822164011.GA7093@kroah.com>

On Thu, Aug 22, 2019 at 09:40:11AM -0700, Greg KH wrote:
> On Fri, Aug 09, 2019 at 12:54:34AM +0900, Suwan Kim wrote:
> > vhci doesn’t do DMA for remote device. Actually, the real DMA
> > operation is done by network card driver. vhci just passes virtual
> > address of the buffer to the network stack, so vhci doesn’t use and
> > need dma address of the buffer of the URB.
> > 
> > But HCD provides DMA mapping and unmapping function by default.
> > Moreover, it causes unnecessary DMA mapping and unmapping which
> > will be done again at the NIC driver and it wastes CPU cycles.
> > So, implement map_urb_for_dma and unmap_urb_for_dma function for
> > vhci in order to skip the DMA mapping and unmapping procedure.
> > 
> > When it comes to supporting SG for vhci, it is useful to use native
> > SG list (urb->num_sgs) instead of mapped SG list because DMA mapping
> > fnuction can adjust the number of SG list (urb->num_mapped_sgs).
> > And vhci_map_urb_for_dma() prevents isoc pipe from using SG as
> > hcd_map_urb_for_dma() does.
> > 
> > Signed-off-by: Suwan Kim <suwan.kim027@gmail.com>
> 
> Can you please redo this patch based on my usb-next branch that has
> Christoph's DMA changes in it?  It should make your change much simpler
> and smaller.
> 
> Please do that and resend the whole series.

I just sent v6 patch. And I discarded patch1 and patch1 is no longer
needed because vhci doesn't set set HCD_DMA flag that is introduced
by Christoph's patch.
So I sent only patch 2 as v6.

Regards
Suwan Kim

  reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-08 15:54 [PATCH v5 0/2] usbip: Implement SG support Suwan Kim
2019-08-08 15:54 ` [PATCH v5 1/2] usbip: Skip DMA mapping and unmapping for urb at vhci Suwan Kim
2019-08-08 16:18   ` shuah
2019-08-13 18:34     ` shuah
2019-08-22 16:40   ` Greg KH
2019-08-22 22:19     ` Suwan Kim [this message]
2019-08-08 15:54 ` [PATCH v5 2/2] usbip: Implement SG support to vhci-hcd and stub driver Suwan Kim
2019-08-08 16:21   ` shuah
2019-08-13 18:36     ` shuah
2019-08-22  1:52     ` Suwan Kim
2019-08-14 13:19 ` [PATCH v5 0/2] usbip: Implement SG support Christoph Hellwig
2019-08-15 13:23   ` Greg KH
2019-08-15 14:10     ` shuah
2019-08-15 15:25       ` 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=20190822221912.GA5004@localhost.localdomain \
    --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=stern@rowland.harvard.edu \
    --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

Example config snippet for mirrors

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