From d2776827315c3d469b8cb4cec14d58877798daa2 Mon Sep 17 00:00:00 2001 From: Stefan Althoefer Date: Sun, 7 Dec 2008 19:39:11 +0100 Subject: USB: descriptor handling MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Remy Böhmer --- include/usb.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/usb.h') diff --git a/include/usb.h b/include/usb.h index 84a77b2f8ba..510df95d628 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 { -- cgit v1.2.3