On Sun, Aug 22, 2010 at 12:05 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Sat, 21 Aug 2010, Maulik Mankad wrote: > >> > I can't tell if it would be correct here, but have you considered just >> > calling unmap_urb_for_dma() instead? (You'd have to make that routine >> > non-static and EXPORT it first.) >> > >> >> Yes I did exactly that as a first step. It worked. >> >> Then found that only dma_unmap_page() is necessary since the >> map_urb_for_dma() function >> does a page mapping using dma_map_page() at least for Storage and HID use cases. >> >> I tested this with Storage and HID classes. >> >> What I may be missing is some class driver which might be using dma_map_sg() or >> other such routine to map the DMA buffers. Is there such a possibility? > > All the mappings are done in map_urb_for_dma, except in the case where > the buffer was set up for a coherent mapping. If you always call > unmap_urb_for_dma then you won't have to worry about strange drivers or > exceptional cases. Besides, it means adding less new code than your > patch contains. > Yes thats true. Calling unmap_urb_for_dma() will handle all cases and would be most effective. So is it okay to make it non-static and export it? Will such a patch be acceptable (since it is in core/hcd.c)? Thanks, Maulik -- 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
