[U-Boot] [PATCH] usb: gadget: Fix data aborts during USB ethernet boot

[Marek Vasut]

Dear Joel Fernandes,

> As seen on GCC 4.6 Linaro compiler, control_req buffer is not aligned
> on 4 byte boundaray causing data aborts in eth_setup -> conf_buf
> during dhcp boot over usb_ether. Fix the issue my aligning control_req
> buffer to 4-byte boundary.
> 
> Tested on am335x_evm platform (beaglebone).
> Applies on 2013.10-rc1 branch.
> 
> Cc: Tom Rini <trini at ti.com>
> Signed-off-by: Joel Fernandes <joelf at ti.com>

Please keep me in the CC next time.

> ---
>  drivers/usb/gadget/ether.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/ether.c b/drivers/usb/gadget/ether.c
> index 579893c..251d7b2 100644
> --- a/drivers/usb/gadget/ether.c
> +++ b/drivers/usb/gadget/ether.c
> @@ -849,7 +849,7 @@ static struct usb_gadget_strings	stringtab = {
>  };
> 
>  /*========================================================================
> ====*/ -static u8 control_req[USB_BUFSIZ];
> +static u8 control_req[USB_BUFSIZ] __attribute__ ((aligned(4)));

Please make this cacheline aligned, so we get rid of bounce buffering of the 
requests on stupid hardware.

>  #if defined(CONFIG_USB_ETH_CDC) || defined(CONFIG_USB_ETH_RNDIS)
>  static u8 status_req[STATUS_BYTECOUNT] __attribute__ ((aligned(4)));

This could also use fixing, but the STATUS_BYTECOUNT would need to be up-aligned 
as well then. Some DEFINE_CACHE_ALIGN_BUFFER might help in both cases here.

>  #endif

Best regards,
Marek Vasut