Re: [Qemu-devel] [PATCH] RFC: hcd-ohci: add dma error handling

[Benjamin Herrenschmidt]

On Wed, 2013-07-17 at 19:46 +1000, Alexey Kardashevskiy wrote:
> Current hcd-ohci does not handle DMA errors which can actually
> happen.
> 
> However it is not clear what approach should be used here -
> for example, get_dwords returns positive number saying that there
> is no error as all the callers consider the return value as fail
> if it is less than zero. Normally you would expect bool=true/int=0
> as success and bool=false/int=-1 as fail.
> 
> Any suggestion?

The right thing to do is not only to bring the error up the stack, but
essentially to set the error bits in the PCI command status and put the
whole HCI in error state (and stop operating)

That how real HW reacts.

Cheers,
Ben.