[U-Boot] [PATCH V2] usb: ci_udc: Allocate the qTD list directly

[Marek Vasut]

On Tuesday, July 01, 2014 at 05:03:17 PM, Stephen Warren wrote:
> On 06/30/2014 06:04 PM, Marek Vasut wrote:
> > Instead of weird allocation of ci_drv->items_mem and then even weirder
> > distribution of offsets in this memory area into ci_drv->items array,
> > just allocate ci_drv->items as a big slab of aligned memory (replaces
> > ci_drv->items_mem) and let ci_get_qtd() do the distribution of offsets
> > in this memory area.
> 
> As I mentioned on IRC, this patch isn't correct.
> 
> The existing code ensures that each pair of QTDs are correctly aligned,
> hence the slight complexity. The new code only actively ensures that the
> first QTD is correctly aligned; the subsequent QTDs will only be
> correctly aligned if the sizeof the QTD structure is an exact multiple
> of the alignment requirements. In practice, it is on my system at least,
> but that may not be generally true.

It is on every system with 32b cachelines. On system with 64b cachelines, you 
won't be able to use one endpoint as both in and out, which I don't think is 
doable now either.

Best regards,
Marek Vasut