From: Johannes Berg <johannes@sipsolutions.net>
To: Hin-Tak Leung <htl10@users.sourceforge.net>
Cc: Larry Finger <Larry.Finger@lwfinger.net>,
Serafeim Zanikolas <sez@debian.org>,
herton@mandriva.com.br, linville@tuxdriver.com, joe@perches.com,
davem@davemloft.net, linux-wireless@vger.kernel.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drivers: rtl818x: request DMA-able memory
Date: Mon, 25 Oct 2010 16:23:04 +0200 [thread overview]
Message-ID: <1288016584.3716.2.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <4CC5900A.2050209@users.sourceforge.net>
On Mon, 2010-10-25 at 15:11 +0100, Hin-Tak Leung wrote:
> >> Despite the indicated intention in comment, the kmalloc() call was not
> >> explicitly requesting memory from ZONE_DMA.
> I had a quick look for similiar constructs and AFAIK only the b43/b43legacy
> drivers uses DMA buffers. Seems to be a rare practice. Is that something we
> should or should not do?
I think there's some confusion here about ZONE_DMA vs. DMA-able memory.
All memory you get with kmalloc can be used for DMA, GFP_DMA means using
ZONE_DMA which is a hack for ISA (and in b43 maybe PCMCIA/Cardbus)
devices to put memory into something they can address. I don't think the
latter is necessary for USB devices.
johannes
next prev parent reply other threads:[~2010-10-25 14:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1287952327-9924-1-git-send-email-sez@debian.org>
2010-10-25 13:24 ` [PATCH] drivers: rtl818x: request DMA-able memory Larry Finger
2010-10-25 14:11 ` Hin-Tak Leung
2010-10-25 14:22 ` John W. Linville
2010-10-25 15:39 ` Hin-Tak Leung
[not found] ` <902045.66378.qm-gyycVyw5OoDyX4RqAA4FmIglqE1Y4D90QQ4Iyu8u01E@public.gmane.org>
2010-10-25 18:01 ` Larry Finger
2010-10-25 17:44 ` Serafeim Zanikolas
2010-10-25 14:23 ` Johannes Berg [this message]
2010-10-25 13:35 ` John W. Linville
2010-10-24 20:32 Serafeim Zanikolas
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