From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 1/4] dmaengine: mmp-pdma support
Date: Wed, 15 Aug 2012 09:04:16 +0100 [thread overview]
Message-ID: <20120815080416.GH18957@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <CAMj5Bkhu2r_R6q3g2aJk1r9Ytz+1eK7gfy6vWuAg1+OPUN7z8Q@mail.gmail.com>
On Wed, Aug 15, 2012 at 03:44:35PM +0800, zhangfei gao wrote:
> Still have one question.
> vchan_tx_submit is sending vd node to submitted list.
> list_add_tail(&vd->node, &vc->desc_submitted);
>
> While what we want is send the desc chain, including many nodes,
> and the first desc will have call back.
> chain 1: first -> desc -> desc -> desc
> chain 2: first -> desc -> desc -> desc
> Once the dma chain done, irq happen and call back from first desc.
I don't understand why you want a DMA engine descriptor to represent
one single DMA hardware scatterlist entry. This makes much more
difficult when reporting status, especially the DMA residue (which
your existing driver does not support.)
Why not hang several DMA hardware scatterlist entries off the same
DMA engine descriptor?
next prev parent reply other threads:[~2012-08-15 8:04 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-14 4:11 [PATCH v3 0/4] dmaengine: add support mmp-pdma Zhangfei Gao
2012-08-14 4:11 ` [PATCH v3 1/4] dmaengine: mmp-pdma support Zhangfei Gao
2012-08-14 8:30 ` Russell King - ARM Linux
2012-08-15 7:44 ` zhangfei gao
2012-08-15 8:04 ` Russell King - ARM Linux [this message]
2012-08-15 9:09 ` zhangfei gao
2012-08-14 9:33 ` Arnd Bergmann
2012-08-14 4:11 ` [PATCH v3 2/4] dmaengine: mmp_tdma: add dt support Zhangfei Gao
2012-08-14 9:34 ` Arnd Bergmann
2012-08-15 7:47 ` zhangfei gao
2012-08-14 4:11 ` [PATCH v3 3/4] dmatest: add dmaengine_slave_config for DMA_MEMCPY Zhangfei Gao
2012-08-14 8:20 ` Russell King - ARM Linux
2012-08-15 7:29 ` zhangfei gao
2012-08-14 4:11 ` [PATCH v3 4/4] mtd: pxa3xx-nand: replace pxa_request_dma with dmaengine Zhangfei Gao
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