From: Oliver Neukum <oliver-GvhC2dPhHPQdnm+yROfE0A@public.gmane.org>
To: Greg KH <greg-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
Cc: Martin Fuzzey <mfuzzey-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
"Russell King - ARM Linux"
<linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>,
"linux-usb" <linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: Problem with non aligned DMA in usbnet on ARM
Date: Wed, 11 Aug 2010 21:10:05 +0200 [thread overview]
Message-ID: <201008112110.05542.oliver@neukum.org> (raw)
In-Reply-To: <20100811174238.GA12382-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
Am Mittwoch 11 August 2010 19:42:38 schrieb Greg KH:
> > So the question is are hcds expected to accept arbitarilly aligned but
> > heap allocated pointers (such as the result of kmalloc() + 1)?
>
> It sounds like your HCD doesn't like this, so perhaps we should make
> that rule :)
>
> If you allocate the urb with a kmalloc() call with no offset, does it
> all work properly? The driver should be calling usb_alloc_urb() which
> does this automatically for them, right? Or is it trying to allocate
> things on its own somehow?
The buffer is the problem not the URB. And up to now the alignment
was not specified, but drivers are generally written assuming byte
granularity.
Regards
Oliver
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next prev parent reply other threads:[~2010-08-11 19:10 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-11 9:41 Problem with non aligned DMA in usbnet on ARM Martin Fuzzey
[not found] ` <AANLkTi=ycg=adcizNWKMCb7EdfDANM=6Es7r_gF1LbhV-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2010-08-11 9:54 ` Russell King - ARM Linux
2010-08-11 10:11 ` Martin Fuzzey
2010-08-11 15:04 ` Greg KH
2010-08-11 16:08 ` Martin Fuzzey
[not found] ` <AANLkTimmJDKbh3_pRY_ASKvjsf4YuuUMh3edh5LvDv-p-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2010-08-11 17:42 ` Greg KH
[not found] ` <20100811174238.GA12382-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2010-08-11 19:07 ` Martin Fuzzey
2010-08-11 20:13 ` Greg KH
[not found] ` <20100811201332.GB10379-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2010-08-11 22:31 ` Martin Fuzzey
2010-08-12 17:01 ` Matthieu CASTET
2010-08-11 19:10 ` Oliver Neukum [this message]
2010-08-11 9:59 ` Matthieu CASTET
[not found] ` <4C627479.4060400-ITF29qwbsa/QT0dZR+AlfA@public.gmane.org>
2010-08-11 11:38 ` Martin Fuzzey
[not found] ` <4C62C7B3.2030706@nvidia.com>
[not found] ` <20100811203505.GA463@n2100.arm.linux.org.uk>
[not found] ` <20100811203505.GA463-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2010-08-11 22:20 ` Martin Fuzzey
2010-08-11 22:47 ` Russell King - ARM Linux
[not found] ` <4C632217.9000608-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2010-08-12 17:08 ` Matthieu CASTET
2010-08-13 10:06 ` Martin Fuzzey
[not found] ` <4C65193E.4090807-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2010-08-13 10:58 ` Oliver Neukum
[not found] ` <201008131258.55016.oneukum-l3A5Bk7waGM@public.gmane.org>
2010-08-13 13:42 ` David Brownell
[not found] ` <732137.54230.qm-g47maUHHHF/6X00i2u5GFvu2YVrzzGjVVpNB7YpNyf8@public.gmane.org>
2010-08-13 13:53 ` Oliver Neukum
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