[U-Boot-Users] [PATCH] Setting processor endianess for USB modules

[Christian Eggers]

Dear Markus,

> Dear Christian,
> 
> "Christian Eggers" <ceggers at gmx.de> writes:
> 
> > I've recognized that a lot of USB code in U-Boot uses the macros
> > swap_16() and swap_32() which are defined in usb.h. The behaviour
> > of the macros is controlled by the define LITTLEENDIAN.
> >
> > Is there a good reason NOT to use the macros provided in
> > asm/byteorder.h (as in the appropriate code in Linux-2.4 )? 
> 
> Largely not. But be carefull. Besides big and little endian CPUs we also
> have controllers that operate in big or little endian (see
> CFG_OHCI_BE_CONTROLLER), and then there are PCI controllers whose
> registers need to be accessed as little endian
> (CFG_OHCI_SWAP_REG_ACCESS).

I didn't change much in usb_ohci.c. But I think there has been a small
error with byteorder conversion (see patch).

> But your right, there is no real for LITTLEENDIAN.
> 
> > I think that switching to these functions might be useful in order
> > to eliminate the need to use the LITTLEENDIAN define for
> > specifying the byteorder. It seems that LITTLEENDIAN is not
> > used outside the USB code.
> 
> Right. Patches cleaning this up are more than welcome! Please note that
> cleaning up USB drivers under the cpu/ directory is a waste of time
> though. Boards using these drivers should be converted to use the
> generic infrastructure in drivers/usb/ instead.

The main focus of my patch is on common/usb.c, common/usb_kbd.c and
common/usb_storage.c. Unfortunately I couldn't test my changes in
usb_kbd.c because I don't have such a device.

Removing the LITTLEENDIAN define seems not to be as easy as I thought
first. A bunch of other modules use the swap_16() and swap_32() defines
from usb.h so I wasn't able to remove these for now.

regards
Christian Eggers


Signed-off-by: Christian Eggers <christian.eggers at kathrein.de>


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