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author | Stefan Althoefer <stefan.althoefer@web.de> | 2008-12-07 21:39:11 +0300 |
---|---|---|
committer | Remy Böhmer <linux@bohmer.net> | 2008-12-09 23:26:45 +0300 |
commit | d2776827315c3d469b8cb4cec14d58877798daa2 (patch) | |
tree | f3bd16ef6c968e1445823fc7b4237a109a718b05 /include | |
parent | dedacc18a8c2b3951581eb721fa055a4e0ac4845 (diff) | |
download | u-boot-d2776827315c3d469b8cb4cec14d58877798daa2.tar.xz |
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')
-rw-r--r-- | include/usb.h | 2 |
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 { |