From: Matthieu CASTET <matthieu.castet-ITF29qwbsa/QT0dZR+AlfA@public.gmane.org>
To: "Patra, Nilkesh" <nilkesh.patra-l0cyMroinI0@public.gmane.org>
Cc: "linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>,
"Gadiyar, Anand" <gadiyar-l0cyMroinI0@public.gmane.org>
Subject: Re: [RFC] MUSB: Workaround for Ethernet data alignment issue
Date: Tue, 15 Dec 2009 11:28:11 +0100 [thread overview]
Message-ID: <4B2764BB.3010306@parrot.com> (raw)
In-Reply-To: <4B276145.1080909-ITF29qwbsa/QT0dZR+AlfA@public.gmane.org>
Matthieu CASTET a écrit :
> Hi,
>
> Patra, Nilkesh a écrit :
>> On the latest version of MUSB, DMA is not working properly if the Data in the packet doesn't start at 32bit aligned address. This issue was found while using MUSB as g_ether. The basic ping does not work, if the data in the Ethernet packet does not start at 32bit aligned address.
>>
>> To overcome this issue, we found one solution mentioned in the below patch. This patch moves data (skb->data) by 2 bytes backwards in ethernet packet, which is nothing but skb->head.
>>
>> I want to know, if there are any better approaches to fix this issue.
>>
> What dma_mask are you using ?
>
>>From what I understand, dma_map_single will use it to know if the dma
> buffer need to be aligned [1].
> So you need to set the last 2 bits to 0 and it should do everything for you.
>
Forget what I said it is only true in CONFIG_DMABOUNCE case...
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
prev parent reply other threads:[~2009-12-15 10:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-14 4:50 [RFC] MUSB: Workaround for Ethernet data alignment issue Patra, Nilkesh
[not found] ` <B85A65D85D7EB246BE421B3FB0FBB59301DEAB8723-/tLxBxkBPtCIQmiDNMet8wC/G2K4zDHf@public.gmane.org>
2009-12-14 17:39 ` Pandita, Vikram
2009-12-14 20:30 ` Sonasath, Moiz
2009-12-16 7:11 ` Patra, Nilkesh
2009-12-15 10:13 ` Matthieu CASTET
[not found] ` <4B276145.1080909-ITF29qwbsa/QT0dZR+AlfA@public.gmane.org>
2009-12-15 10:28 ` Matthieu CASTET [this message]
Reply instructions:
You may reply publicly 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=4B2764BB.3010306@parrot.com \
--to=matthieu.castet-itf29qwbsa/qt0dzr+alfa@public.gmane.org \
--cc=david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org \
--cc=gadiyar-l0cyMroinI0@public.gmane.org \
--cc=linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=nilkesh.patra-l0cyMroinI0@public.gmane.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox