From: Arvid Brodin <arvid.brodin@enea.com>
To: linux-kernel@vger.kernel.org
Cc: linux-embedded@vger.kernel.org,
Hans-Christian Egtvedt <egtvedt@samfundet.no>,
Haavard Skinnemoen <hskinnemoen@gmail.com>,
arnd@arndb.de
Subject: Re: dma_unmap_single() lacking cache sync on some archs?
Date: Tue, 27 Sep 2011 14:13:34 +0200 [thread overview]
Message-ID: <4E81BDEE.2080601@enea.com> (raw)
[Resending with CC to affected parties]
Hi,
I would expect cache synchronization for DMA_TO_DEVICE and DMA_BIDIRECTIONAL
when dma_map_single() is called, and for DMA_FROM_DEVICE and DMA_BIDIRECTIONAL
when dma_unmap_single() is called.
However, on some architechtures (at least avr32, blackfin, ...), cache
synchronization only happens when dma_map_single() is called (and then
irrespective of DMA direction). dma_unmap_single() is a no-op for these archs.
See e.g. http://lxr.linux.no/#linux+v3.0.4/arch/avr32/include/asm/dma-mapping.h#L117
Isn't this a bug?
(Please CC me in responses.)
--
Arvid Brodin
Enea Services Stockholm AB
WARNING: multiple messages have this Message-ID (diff)
From: Arvid Brodin <arvid.brodin@enea.com>
To: <linux-kernel@vger.kernel.org>
Cc: <linux-embedded@vger.kernel.org>,
Hans-Christian Egtvedt <egtvedt@samfundet.no>,
Haavard Skinnemoen <hskinnemoen@gmail.com>, <arnd@arndb.de>
Subject: Re: dma_unmap_single() lacking cache sync on some archs?
Date: Tue, 27 Sep 2011 14:13:34 +0200 [thread overview]
Message-ID: <4E81BDEE.2080601@enea.com> (raw)
[Resending with CC to affected parties]
Hi,
I would expect cache synchronization for DMA_TO_DEVICE and DMA_BIDIRECTIONAL
when dma_map_single() is called, and for DMA_FROM_DEVICE and DMA_BIDIRECTIONAL
when dma_unmap_single() is called.
However, on some architechtures (at least avr32, blackfin, ...), cache
synchronization only happens when dma_map_single() is called (and then
irrespective of DMA direction). dma_unmap_single() is a no-op for these archs.
See e.g. http://lxr.linux.no/#linux+v3.0.4/arch/avr32/include/asm/dma-mapping.h#L117
Isn't this a bug?
(Please CC me in responses.)
--
Arvid Brodin
Enea Services Stockholm AB
next reply other threads:[~2011-09-27 12:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-27 12:13 Arvid Brodin [this message]
2011-09-27 12:13 ` dma_unmap_single() lacking cache sync on some archs? Arvid Brodin
2011-09-27 16:55 ` Håvard Skinnemoen
2011-09-27 18:27 ` Arnd Bergmann
2011-09-29 18:56 ` Arvid Brodin
2011-09-29 18:56 ` Arvid Brodin
-- strict thread matches above, loose matches on Subject: below --
2011-09-22 0:18 Arvid Brodin
2011-09-22 22:06 ` Guennadi Liakhovetski
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