> -----Original Message----- > From: Oliver Neukum [mailto:oliver@xxxxxxxxxx] > Sent: Wednesday, February 17, 2010 2:41 PM > To: Shilimkar, Santosh > Cc: Russell King - ARM Linux; Catalin Marinas; Pavel Machek; Greg KH; Matthew Dharm; Sergei Shtylyov; > Ming Lei; Sebastian Siewior; linux-usb@xxxxxxxxxxxxxxx; linux-kernel; linux-arm-kernel; Mankad, > Maulik Ojas; Gadiyar, Anand > Subject: Re: USB mass storage and ARM cache coherency > > Am Mittwoch, 17. Februar 2010 09:55:08 schrieb Shilimkar, Santosh: > > > Your original patch however kills ehci, ohci and uhci on some architectures. > > > > How about below approach? Controller driver can set > > "uses_pio_for_control" if it can't do dma for control transfer. > > > > diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c > > index 80995ef..e3eae02 100644 > > --- a/drivers/usb/core/hcd.c > > +++ b/drivers/usb/core/hcd.c > > @@ -1276,7 +1276,7 @@ static int map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb, > > > > if (usb_endpoint_xfer_control(&urb->ep->desc) > > && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP)) { > > - if (hcd->self.uses_dma) { > > + if (hcd->self.uses_dma && !hcd->self.uses_pio_for_control) { > > It is not elegant to describe exceptions. It would be better, if you split up > the flag into two flags, called uses_dma_for_ordinary_transfers and > uses_dma_for control_transfers. Doing so also makes sure you look at > all hcd drivers ;-) > Good point. Negative checks are any way not elegant > And the tests become straightforward. And please add a detailed comment > to explain why this differentiation is needed on ARM. OK. I shall create a patch with description about the problem. Thanks for feedback!! Regards, Santosh -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
