On Tue, Dec 20, 2011 at 05:23:58PM +0100, Sebastian Andrzej Siewior wrote: > * Alan Stern | 2011-12-20 10:54:41 [-0500]: > > >On Tue, 20 Dec 2011, Felipe Balbi wrote: > > > >> If we're using an IN endpoint, the DMA direction > >> is DMA_FROM_DEVICE, rather than DMA_TO_DEVICE. > > > >Are you sure you haven't got this backward? > > > >For DMA operations, the device is the thing doing the direct memory > >access -- in this case, the UDC controller. With IN endpoints, data > >goes from the gadget's memory, though the UDC controller, and over the > >USB bus to the host. That is _from_ memory _to_ UDC; hence the > >direction is DMA_TO_DEVICE. > > The spec says: > DMA_TO_DEVICE data is going from the memory to the device > DMA_FROM_DEVICE data is coming from the device to the memory > > So for IN endpoint we need DMA_TO_DEVICE because it goes from memory to > device. > Thanks Alan. Yeah, I went read the Documentation too and found out the same. Dropped the patch from my list. Does it mean we have a bug on Renesas' driver ? diff --git a/drivers/usb/renesas_usbhs/mod_gadget.c b/drivers/usb/renesas_usbhs/mod_gadget.c index 7f4e803..991c29c 100644 --- a/drivers/usb/renesas_usbhs/mod_gadget.c +++ b/drivers/usb/renesas_usbhs/mod_gadget.c @@ -232,7 +232,7 @@ static int usbhsg_dma_map_ctrl(struct usbhs_pkt *pkt, int map) struct device *dev = usbhsg_gpriv_to_dev(gpriv); enum dma_data_direction dir; - dir = usbhs_pipe_is_dir_in(pipe) ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + dir = usbhs_pipe_is_dir_in(pipe) ? DMA_TO_DEVICE : DMA_FROM_DEVICE; if (map) return usbhsg_dma_map(dev, pkt, dir); Kuninori, can you comment ? -- balbi
Attachment:
signature.asc
Description: Digital signature
