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

[Marek Vasut]

Dear Joel Fernandes,

> On 08/27/2013 08:52 AM, Marek Vasut wrote:
> > 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.
> 
> Ok.
> 
> >> ---
> >> 
> >>  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.
> 
> Ok, how about __aligned(CONFIG_SYS_CACHELINE_SIZE) instead of defining
> a new DEFINE_CACHE_ALIGN_BUFFER macro?

THis is already defined and used throughout the USB code, check include/common.h 
IIRC.

> Can you explain what you meant by STATUS_BYTECOUNT up-aligned and why its
> needed to be up-aligned?

it's 16 bytes now, no? Up-align it to cacheline size.

Best regards,
Marek Vasut