Re: USB mass storage and ARM cache coherency

From: Oliver Neukum
Date: Wed Feb 17 2010 - 05:23:35 EST


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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