Re: [RFC PATCH] usb: hcd: warn about URB buffers that are not DMA aligned and are about to be DMA mapped
From: Jussi Kivilinna <hidden>
Date: 2013-06-16 10:35:40
Possibly related (same subject, not in this thread)
- 2013-06-16 · Re: [RFC PATCH] usb: hcd: warn about URB buffers that are not DMA aligned and are about to be DMA mapped · Jussi Kivilinna <hidden>
- 2013-06-15 · Re: [RFC PATCH] usb: hcd: warn about URB buffers that are not DMA aligned and are about to be DMA mapped · Ming Lei <tom.leiming@gmail.com>
- 2013-06-15 · Re: [RFC PATCH] usb: hcd: warn about URB buffers that are not DMA aligned and are about to be DMA mapped · Jussi Kivilinna <hidden>
- 2013-06-15 · Re: [RFC PATCH] usb: hcd: warn about URB buffers that are not DMA aligned and are about to be DMA mapped · Jussi Kivilinna <hidden>
- 2013-06-15 · Re: [RFC PATCH] usb: hcd: warn about URB buffers that are not DMA aligned and are about to be DMA mapped · Ming Lei <hidden>
On 16.06.2013 11:21, Oliver Neukum wrote:
On Saturday 15 June 2013 16:22:30 Jussi Kivilinna wrote:quoted
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.
Ok, I'll look at that direction. Thanks. -Jussi
Regards Oliver