On 10/01/2011 11:22 AM, Christian Lamparter wrote:
On Saturday 01 October 2011 18:01:08 Larry Finger wrote:
Ian,
Most of the skb assignments in r8712u are aligned OK and most aligned on
512-byte boundaries, but there was one that had the minimal offset of 14 bytes.
The attached patch should fix it. Does it help?
Interesting, this "patch" goes in a completely different direction.
Can you tell me where the driver aligns the frames which will be
xmitted by the device [i.e.: which is passed to the usb subsystem
by usb_submit_urb]? Because that's what actually matters.
In this driver, all references are to _usb_submit_urb(), which is defined to be
usb_submit_urb() in one of the header files. That made it easy to insert a test
for misalignment of the DMA buffer as follows:
Index: wireless-testing-new/drivers/staging/rtl8712/osdep_service.h
===================================================================
--- wireless-testing-new.orig/drivers/staging/rtl8712/osdep_service.h
+++ wireless-testing-new/drivers/staging/rtl8712/osdep_service.h
@@ -34,7 +34,7 @@
#include <linux/if_arp.h>
#include <linux/firmware.h>
#define _usb_alloc_urb(x, y) usb_alloc_urb(x, y)
-#define _usb_submit_urb(x, y) usb_submit_urb(x, y)
+//#define _usb_submit_urb(x, y) usb_submit_urb(x, y)
struct __queue {
struct list_head queue;
@@ -232,5 +232,13 @@ static inline u32 _RND512(u32 sz)
return ((sz >> 9) + ((sz & 511) ? 1 : 0)) << 9;
}
+static inline int _usb_submit_urb(struct urb *urb, gfp_t mem_flags)
+{
+ if (urb->transfer_dma & 3) {
+ pr_info("Transfer_dma 0x%x not on 4-byte boundary\n",
(uint)urb->transfer_dma);
+ dump_stack();
+ }
+ return usb_submit_urb(urb, mem_flags);
+}
#endif
I never hit the pr_info() and the associated dump_stack(). If that test is
sufficient, then buffer misalignment is not the source of the problem.
Larry
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