From: phind.uet@gmail.com (phind.uet at gmail.com)
To: kernelnewbies@lists.kernelnewbies.org
Subject: Question about DMA mapping.
Date: Fri, 31 Aug 2018 08:53:29 +0800 [thread overview]
Message-ID: <498566ed-6ac7-a31c-e540-9974a0796ed2@gmail.com> (raw)
Hi everyone,
Thank for your time, I'm new to linux kernel. I am reading LDD3 chapter
15, Dirrect Memory Access section. I see that when I call function
/dma_map_single/ and /dma_unmap_single/, I need to pass a direction as a
parameter. I wonder what is purpose of it? Does It relate to something
like permission? Can I call /dma_map_single /with DMA_BIDIRECTIONAL and
then call /dma_unmap_single /with DMA_TO_DEVICE? Will it cause any problem?
Thank you very much.
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Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-31 0:53 phind.uet at gmail.com [this message]
2018-08-31 14:09 ` Question about DMA mapping valdis.kletnieks at vt.edu
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