Messages in this thread | | | From | Oliver Neukum <> | Subject | Re: usb_get_status(): what a weird implementation ! | Date | Mon, 30 Jun 2008 15:51:41 +0200 |
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Am Montag 30 Juni 2008 14:41:37 schrieb Francis Moreau: > On Mon, Jun 30, 2008 at 1:46 PM, Oliver Neukum <oliver@neukum.org> wrote: > > Am Montag 30 Juni 2008 13:04:21 schrieb Francis Moreau:
> >> well, it wouldn't be hard to allocated a buf on the stack with correct > >> alignement > >> and size for DMA mapping. > > > > Where would you put it and meet the alignment requirements? > > > > wouldn't this code below do the trick ? > > void foo(void) > { > unsigned char __buf[2 * CACHE_LINE_SIZE]; > unsigned char *buf; > > buf = ((unsigned long)__buf) + CACHE_LINE_SIZE-1) & ~(CACHE_LINE_SIZE-1); > } > > but I agree it looks hackish.
If your buffer is smaller than CACHE_LINE_SIZE it should work. However, this needs input from people who understand DMA in and out. But how large is 2 * CACHE_LINE_SIZE compared to the kernel stack?
Regards Oliver
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