On Thu, 11 Aug 2005, Juergen Schindele wrote:
> Am Mittwoch, 10. August 2005 16:48 schrieb Alan Stern:
> First thanks for your reply .
>
> > The driver doesn't utilize this buffer as much as it could. It should set
> > touchkit->irq->transfer_dma to touchkit->data_dma and
> > touchkit->irq->transfer_flags to URB_NO_TRANSFER_DMA_MAP. However, even
> > without setting those things the transfer should still work okay.
> So i did the following :
>
> touchkit->irq = usb_alloc_urb(0, GFP_KERNEL);
>
> touchkit->data = usb_buffer_alloc(udev, TOUCHKIT_REPORT_DATA_SIZE,
> SLAB_ATOMIC | URB_NO_TRANSFER_DMA_MAP,
> &touchkit->irq->transfer_dma);
>
> usb_fill_int_urb(touchkit->irq, touchkit->udev,
> usb_rcvintpipe(touchkit->udev, 0x81),
> touchkit->data, TOUCHKIT_REPORT_DATA_SIZE,
> touchkit_irq, touchkit, endpoint->bInterval);
>
> But it still dont work like it should. :-(
>
> > That's not a static array, because it's part of the dynamically-allocated
> > touchkit structure.
> Ok you are right !
>
> > I don't see how. In both cases you told the driver where to put the data.
> > In one case the data ended up where you wanted, in the other case it
> > didn't. It shouldn't matter how you got the data buffer in the first
> > place -- unless dma_alloc_coherent for some reason returned memory that
> > isn't accessible for DMA (which can't happen on x86).
>
> Unfortunaterly i am not on ix86. So dma_alloc_coherent can fail !?
Ah, yes. I didn't notice in the subject line you mentioned you're using
the PXA-270. I don't know if dma_alloc_coherent can fail on PXA. You
should test the address you get back to see if it is NULL.
You should also add this line to the driver:
touchkit->irq->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
right after usb_fill_int_urb(). Maybe then it will work correctly.
Alan Stern
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