Re: [PATCH] DMA: Correct invalid assumptions in the Kconfig text

Dan Williams
2007-10-26T17:02:41Z

On 10/25/07, Haavard Skinnemoen <hskinnemoen@atmel.com> wrote:
> On Wed, 24 Oct 2007 20:16:16 +0200
> Haavard Skinnemoen <hskinnemoen@atmel.com> wrote:
>
> > [handwaving about API extensions]
>
> Oh, and we definitely need a way to report errors. Looks like the
> existing drivers want this as well -- I couldn't help but notice this
> in the iop-adma driver:
>
> static irqreturn_t iop_adma_err_handler(int irq, void *data)
> {
> (...)
>
> BUG();
> }
>
> That's a panic waiting to happen, isn't it?

Yes, and it should have a comment, because for now this is deliberate.
This was primarily driven by the fact that MD has no way of
recovering from hardware errors during software-memcpy or
software-xor_blocks so there was no where to plug-in
accelerated-memcpy/xor error recovery. I can foresee other clients
wanting to have this information reported but async_tx based clients
are supposed to be blissfully unaware of under the covers hardware
acceleration.

One idea is to pass an error-pointer as the parameter to callback
routines, but that would hamper the client's ability to recover the
context of the failure...

>
> Håvard

--
Dan