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authorStefan Althoefer <stefan.althoefer@web.de>2008-12-07 19:39:11 +0100
committerRemy Böhmer <linux@bohmer.net>2008-12-09 21:26:45 +0100
commitd2776827315c3d469b8cb4cec14d58877798daa2 (patch)
treef3bd16ef6c968e1445823fc7b4237a109a718b05 /include/usb.h
parentdedacc18a8c2b3951581eb721fa055a4e0ac4845 (diff)
USB: descriptor handling
Hi, I found a bug when working with the u-boot USB subsystem on IXP425 processor (big endian Xscale aka ARMv5). I recognized that the second usb_endpoint_descriptor of the attached memory stick was corrupted. The reason for this are the packed structures below (either u-boot and u-boot-usb): -------------- /* Endpoint descriptor */ struct usb_endpoint_descriptor { unsigned char bLength; unsigned char bDescriptorType; unsigned char bEndpointAddress; unsigned char bmAttributes; unsigned short wMaxPacketSize; unsigned char bInterval; unsigned char bRefresh; unsigned char bSynchAddress; } __attribute__ ((packed)); /* Interface descriptor */ struct usb_interface_descriptor { unsigned char bLength; unsigned char bDescriptorType; unsigned char bInterfaceNumber; unsigned char bAlternateSetting; unsigned char bNumEndpoints; unsigned char bInterfaceClass; unsigned char bInterfaceSubClass; unsigned char bInterfaceProtocol; unsigned char iInterface; unsigned char no_of_ep; unsigned char num_altsetting; unsigned char act_altsetting; struct usb_endpoint_descriptor ep_desc[USB_MAXENDPOINTS]; } __attribute__ ((packed)); ------------ As usb_endpoint_descriptor is only 7byte in length, the start of all odd ep_desc[] structures is not word aligned. This makes wMaxPacketSize of these structures also not word aligned. ARMv5 Architecture however does not support non-aligned multibyte data type (see A2.8 of ARM Architecture Reference Manual). Signed-off-by: Stefan Althoefer <stefan.althoefer@web.de> Signed-off-by: Remy Böhmer <linux@bohmer.net>
Diffstat (limited to 'include/usb.h')
-rw-r--r--include/usb.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/usb.h b/include/usb.h
index 84a77b2f8b..510df95d62 100644
--- a/include/usb.h
+++ b/include/usb.h
@@ -91,7 +91,7 @@ struct usb_endpoint_descriptor {
unsigned char bInterval;
unsigned char bRefresh;
unsigned char bSynchAddress;
-} __attribute__ ((packed));
+} __attribute__ ((packed)) __attribute__ ((aligned(2)));
/* Interface descriptor */
struct usb_interface_descriptor {