Hi,
On Tue, Oct 18, 2011 at 10:57:41AM +0300, ext Yauheni Kaliuta wrote:
> Is there any requirement to device controller driver (struct usb_ep_ops
> implementation) to handle premapped by higher levels (gadget driver)
> usb_request's dma address?
>
> I see, musb driver does it, Fusb300 UDC, for example, doesn't.
Yeah, there's a problem here. In short there's no real requirement set
and each UDC is doing what it thinks is right. This means that in some
controllers we have constructs such as:
#define DMA_ADDR_INVALID ((dma_addr_t) ~(0))
struct usb_request *alloc()
{
req = kzalloc();
req->request.dma = DMA_ADDR_INVALID;
return &req->request;
}
queue()
{
if (request->dma == DMA_ADDR_INVALID)
map();
}
and some won't have that sort of handling... Maybe the best will be
require that UDC map the buffer to DMA. Then we drop all of that
DMA_ADDR_INVALID hackery.
--
balbi
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