Subject: Re: [RFC PATCH] usb: hcd: warn about URB buffers that are not DMA aligned and are about to be DMA mapped

From: Oliver Neukum <[email-masked]>
Date: Sun, 16 Jun 2013 10:21:29 +0200

On Saturday 15 June 2013 16:22:30 Jussi Kivilinna wrote:

> Hm.. rethink this a bit.
> 
> Transfer buffer might be dma aligned but shorter than cacheline and end of cacheline
> used as something else. Manual alignment by host driver does not catch that
> or fix that.
> So, yes.. dma mapping should work with unaligned buffers, but maybe the actual
> problem is multiple buffers from same cacheline.

The buffers kmalloc() returns are OK in that regard. A driver that uses
a buffer for anything but buffering is buggy.

	Regards
		Oliver

--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to [email-masked]
More majordomo info at  http://vger.kernel.org/majordomo-info.html