Re: [patch 6/7] SDHCI: Check DMA for overruns at end of transfer

[Pierre Ossman]

On Mon, 03 Nov 2008 20:09:50 +0000
Ben Dooks <ben-linux@xxxxxxxxx> wrote:

> At the end of a transfer, check that the DMA engine in the
> SDHCI controller actually did what it was meant to and didn't
> overrun the end of the buffer.
> 
> This seems to be triggered by a timeout during an CMD25 (multiple block         
> write) to a card. The mmc_block module then issues a command to find out        
> how much data was moved and this seems to end up triggering this DMA            
> check. The result is the card's queue generates an OOPS as the stack has        
> been trampled on due to the extra data transfered.
> 
> Signed-off-by: Ben Dooks <ben-linux@xxxxxxxxx>

I'm sorry, but I don't see how this is anywhere near acceptable. This
should be a panic at the very least, and until this can be sorted out
and avoided the driver should avoid using DMA on these chips.

-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  rdesktop, core developer          http://www.rdesktop.org

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