Messages in this thread | | | Date | Wed, 22 Jul 2015 10:19:25 +0530 | From | Vinod Koul <> | Subject | Re: [PATCH 08/11] MTD: m25p80: Add option to limit SPI transfer size. |
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On Tue, Jul 21, 2015 at 10:14:11AM +0200, Michal Suchanek wrote: > > Or alternatively we could publish the limitations of the channel using > > capabilities so SPI knows I have a dmaengine channel and it can transfer max N > > length transfers so would be able to break rather than guessing it or coding > > in DT. Yes it may come from DT but that should be dmaengine driver rather > > than client driver :) > > > > This can be done by dma_get_slave_caps(chan, &caps) > > > > And we add max_length as one more parameter to existing set > > > > Also all this could be handled in generic SPI-dmaengine layer so that > > individual drivers don't have to code it in > > > > Let me know if this idea is okay, I can push the dmaengine bits... > > It would be ok if there was a fixed limit. However, the limit depends > on SPI slave settings. Presumably for other buses using the dmaengine > the limit would depend on the bus or slave settings as well. I do not > see a sane way of passing this all the way to the dmaengine driver. I don't see why this should be client (SPI) dependent. The max length supported is a dmaengine constraint, typically flowing from max blocks/length it can transfer. Know this limit can allow clients to split transfers.
-- ~Vinod
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