Messages in this thread | | | From | David Brownell <> | Subject | Re: [PATCH 01/16] Blackfin SPI Driver: ensure cache coherency before doing DMA | Date | Thu, 20 Nov 2008 14:05:06 -0800 |
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On Thursday 20 November 2008, Mike Frysinger wrote: > On Thu, Nov 20, 2008 at 16:47, David Brownell wrote:
> > Basically, dma_map_single(), dma_unmap_single() ... and > > remember that the caller may have done the mappings for > > you already. > > these arent required to provide coherent memory right ? if that's the > case, i can take a look at getting things updated.
Right. If caller provides dma-coherent memory to you, they must also have provided the DMA addresses the controller driver should be using ... so you won't need dma mapping calls on those paths.
> > It'd be nice if one of patches snuck in a comment on that > > point: "Full duplex only works for non-DMA transfers." > > Same rationale: you may know this hardware inside out, > > but the next person won't. > > well, hopefully if they dont know they wont be touching the driver ;). > i'll add a comment in this code chunk. thanks for the feedback.
The way it usually works is someone observes a problem and then starts experimenting on relevant code. So they learn a bit while debugging ... and code authors/maintainers need to keep that learning curve from being too steep. ;)
- Dave
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