[U-Boot] [PATCH 2/2] ehci-hcd.c, musb_core, usb.h: Add USB_DMA_MINALIGN define for cache alignment

Marek Vasut
2012-07-15T09:42:21Z

Dear Ilya Yanok,

> Dear Marek,
>
> On Sun, Jul 15, 2012 at 12:07 PM, Marek Vasut <marex@denx.de> wrote:
> > > > @@ -207,8 +210,8 @@ static int
> > > >
> > > > ehci_submit_async(struct usb_device *dev, unsigned long pipe, void
> > > >
> > > > *buffer,
> > > >
> > > > int length, struct devrequest *req)
> > > >
> > > > {
> > > >
> > > > - static struct QH qh __attribute__((aligned(32)));
> > > > - static struct qTD qtd[3] __attribute__((aligned (32)));
> > > > + ALLOC_CACHE_ALIGN_BUFFER(struct QH, qh, 1);
> > >
> > > Somehow this doesn't work being allocated on stack... I assumed that
> > > this was declared as static just to use __attribute__((aligned))...
> >
> > Not really ... but then, we have indeed a problem here. It was probably
> > declared
> > static to preserve the contents of these variables across the the calls
> > of this
> > function. Sigh, the USB code is really bloody :-/
>
> Hm.. no, I don't think it's about contents... Look, there are memset()
> calls straight in the beginning of the function. It looks like it's about
> qh address: I tried debugging it a bit and it seems to work until qh has
> the same address and break when the address eventually changes.

I see, stupid me. So it's only the address? And I take it the controller doesn't
use those after it leaves the function, right (maybe that might be it) ?

> > Ilya, can you try pulling these out of the function?
>
> I can but what for? Are there any differences (except for scope) declaring
> statics inside or outside function? As I said declaring qh static (with
> DEFINE_CACHE_ALIGN_BUFFER) works but...
>
> Regards, Ilya.

Best regards,
Marek Vasut