On 05/18/2018 06:23 AM, hch@xxxxxx wrote:
Fri, May 18, 2018 at 01:03:46PM +0000, Alexey Brodkin wrote:
Note mmc_get_dma_dir() is just "data->flags & MMC_DATA_WRITE ? DMA_TO_DEVICE : DMA_FROM_DEVICE".
I.e. if we're preparing for sending data dma_noncoherent_map_sg() will have DMA_TO_DEVICE which
is quite OK for passing to dma_noncoherent_sync_sg_for_device() but in case of reading we'll have
DMA_FROM_DEVICE which we'll pass to dma_noncoherent_sync_sg_for_device() in dma_noncoherent_map_sg().
I'd say this is not entirely correct because IMHO arch_sync_dma_for_cpu() is supposed to only be used
in case of DMA_FROM_DEVICE and arch_sync_dma_for_device() only in case of DMA_TO_DEVICE.
arc overrides the dir paramter of the dma_sync_single_for_device/
dma_sync_single_for_cpu calls. My patches dropped that, and I have
restored that, and audit for the other architectures is pending.
Right, for now lets retain that and do a sweeping audit of @direction - to me it
seems extraneous (as it did 10 years ago), but I'm not an expert in this are so
perhaps it is needed for some device / arches and it would be good to understand
that finally.
That being said the existing arc code still looks rather odd as it
didn't do the same thing for the scatterlist versions of the calls.
I've thrown in a few patches into my new tree to make the sg versions
make the normal calls, and to clean up the area a bit.
Not calling names or anything here, but it doesn't exist for sg variants, because
I didn't write that code :-)
It was introduced by your commi:
2016-01-20 052c96dbe33b arc: convert to dma_map_ops
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