Re: [PATCH 1/2] USB: Allow HCDs to specifiy their DMA alignment requirements

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--- On Wed, 9/1/10, Oliver Neukum <oneukum@xxxxxxx> wrote:

> 
> Am Dienstag, 31. August 2010,
> 21:23:05 schrieb David Brownell:
> > I thought the resolution was that any HCD which
> > requires alignment other than 1-byte was buggy;
> > trying to use it would break too many drivers,
> > and try to spread rude constaints to too many
> > subsystems that don't want such stuff any more
> > than the USB stack (doesn't want it).
> 
> True. It is a requirenment that a HCD work with
> any  kmalloced  buffer.

Not what I said at all ... there's a whole bunch
of generic "is this DMA-safe" constraints which
apply to USB just like the rest of Linux, and
none of them include alignment.

Passing a pointer to a few bytes inside of a
kmalloc'd block has always been legit, even if
that pointer isn't aligned to N!=1 bytes.







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