Re: USB mass storage and ARM cache coherency

[Oliver Neukum]

Am Mittwoch, 17. Februar 2010 11:18:01 schrieb Benjamin Herrenschmidt:
> > No problem here. USB core does the mapping only if the low-level driver
> > so requests. The only exception is in usb_buffer_alloc(), but that boils
> > down to dma_alloc_coherent() 
> 
> Allright, so why do we need to "fix" anything ? Or is the whole thread
> moot ? :-)

The request a low-level driver does is all or nothing. Either DMA
issues have to be handled by that driver alone, or a finer-grained
description of the DMA requirements is needed. A fix using the latter
approach is being worked on.

	Regards
		Oliver
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