Re: [PATCH] usb: dma bounce buffer support V2

[Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>]

On Thu, 17 Jan 2008, Magnus Damm wrote:

> usb: dma bounce buffer support V2
> 
> This patch adds dma bounce buffer support to the usb core. These buffers
> can be enabled with the HCD_LOCAL_MEM flag, and they make sure that all data
> passed to the host controller is allocated using dma_alloc_coherent().

This looks good.  Just one little change:

> +static int map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
> +			   gfp_t mem_flags)
> +{
...
> +	if (ret == 0 && urb->transfer_buffer_length != 0
> +	    && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) {
> +		if (hcd->self.uses_dma)
>  			urb->transfer_dma = dma_map_single (
>  					hcd->self.controller,
>  					urb->transfer_buffer,
>  					urb->transfer_buffer_length,
> -					usb_urb_dir_in(urb)
> -					    ? DMA_FROM_DEVICE
> -					    : DMA_TO_DEVICE);
> +					dir);
> +		else if (hcd->driver->flags & HCD_LOCAL_MEM)
> +			ret = hcd_alloc_coherent(
> +					urb->dev->bus, mem_flags,
> +					&urb->transfer_dma,
> +					&urb->transfer_buffer,
> +					urb->transfer_buffer_length,
> +					dir);
> +
> +		if (ret && usb_endpoint_xfer_control(&urb->ep->desc)
> +		    && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP)
> +		    && (hcd->driver->flags & HCD_LOCAL_MEM))
> +			hcd_free_coherent(urb->dev->bus,
> +					  &urb->setup_dma,
> +					  (void **)&urb->setup_packet,
> +					  sizeof (struct usb_ctrlrequest),
> +					  DMA_TO_DEVICE);

This last section should be in the scope of the HCD_LOCAL_MEM test above.

Alan Stern


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