dmaengine: pxa: handle bus errors

In the current state, upon bus error the driver will spin endlessly,
relaunching the last tx, which will fail again and again :
 - a bus error happens
 - pxad_chan_handler() is called
 - as PXA_DCSR_STOPSTATE is true, the last non-terminated transaction is
   lauched, which is the one triggering the bus error, as it didn't
   terminate
 - moreover, the STOP interrupt fires a new, as the STOPIRQEN is still
   active

Break this logic by stopping the automatic relaunch of a dma channel
upon a bus error, even if there are still pending issued requests on it.

As dma_cookie_status() seems unable to return DMA_ERROR in its current
form, ie. there seems no way to mark a DMA_ERROR on a per-async-tx
basis, it is chosen in this patch to remember on the channel which
transaction failed, and report it in pxad_tx_status().

It's a bit misleading because if T1, T2, T3 and T4 were queued, and T1
was completed while T2 causes a bus error, the status of T3 and T4 will
be reported as DMA_IN_PROGRESS, while the channel is actually stopped.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

path: root/Documentation/Sponsors

netsniff-ng is partly sponsored by:
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Red Hat
 * W: http://www.redhat.com/

Deutsche Flugsicherung GmbH
 * W: https://secais.dfs.de/

ETH Zurich:
 * W: http://csg.ethz.ch/

Max Planck Institute for Human Cognitive and Brain Sciences
 * W: http://www.cbs.mpg.de/