From mboxrd@z Thu Jan 1 00:00:00 1970 From: jonsmirl@gmail.com (jonsmirl at gmail.com) Date: Wed, 6 Feb 2013 23:27:10 -0500 Subject: DMAEngine and channel pairs Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The CPU I'm working on uses two sequential DMA channels to implement scatter-gather. How do you handle this in the channel allocator? If scatter-gather is not requested the two channels work fine as normal DMA channels. So when a scatter-gather channel is requested my driver needs to fail the dma_alloc_chan_resources() requests until a sequential pair is located? Plus I need to track what channels are used in my driver so that I know where sequential pairs are. Is there a better way to do this? Another solution might be to statically allocate some channels as being scatter/gather capable and others as not being able to do it. I would just report fewer available channels to dmaengine and hide those secondary channels from it. I have 12 channels to work with. -- Jon Smirl jonsmirl at gmail.com