Messages in this thread | | | From | Tomasz Figa <> | Subject | Re: [PATCH 10/18] spi: s3c64xx: Do not require legacy DMA API in case of S3C64XX | Date | Tue, 13 Aug 2013 22:20:19 +0200 |
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On Tuesday 13 of August 2013 21:18:16 Mark Brown wrote: > On Tue, Aug 13, 2013 at 07:55:47PM +0100, Mark Brown wrote: > > I'm still debugging what's going on here - the basic refcounting all > > looks OK in the SPI driver, I can see it requesting and releasing with > > the refcounts all going back to zero in the DMA driver as expected but > > when we come back to the device later on dmaengine is deciding the > > device is unavailable quite early on in the process. > > The failure is happening because this check is failing: > > /* devices with multiple channels need special handling as we need to > * ensure that all channels are either private or public. > */ > if (dev->chancnt > 1 && !dma_has_cap(DMA_PRIVATE, dev->cap_mask)) > list_for_each_entry(chan, &dev->channels, device_node) { > /* some channels are already publicly allocated */ > if (chan->client_count) { > > which is happening because dma1chan0 (which is on the same DMA > controller as the SPI controller) and in fact every other DMA channel > had references grabbed by the network stack dmaengine helpers which I'd > enabled in config. The fact that they do that is unhelpful, it renders > the API mostly useless, but is nothing to do with this series. > > Having tweaked the config everything appears to work so: > > Tested-by: Mark Brown <broonie@linaro.org> > > though the whole thing with the filter function is as I say a bit fun > from a code review point of view.
I believe you just found another brokenness of current DMA channel matching.
Thanks for testing.
Best regards, Tomasz
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