[PATCH v8 04/16] DMA: PL330: Remove the start operation for handling DMA_TERMINATE_ALL command

Jassi Brar wrote:

On 6 September 2011 17:57, Russell King - ARM Linux
[off-list ref] wrote:

quoted

On Tue, Sep 06, 2011 at 05:52:19PM +0530, Jassi Brar wrote:

quoted

On Fri, Sep 2, 2011 at 6:14 AM, Boojin Kim [off-list ref] wrote:

quoted

Origianl code carries out the start operation after flush operation.
But start operation is not required for DMA_TERMINATE_ALL command.
So, This patch removes the unnecessary start operation and only carries out
the flush oeration for handling DMA_TERMINATE_ALL command.

Not exactly. The 'start' is impotent when called from this path because there
is nothing left queued after the call to 'flush'.
pl330_tasklet() is called because that is a common function that does the
house-keeping acc to what's presently in 'work' and 'done' lists.

Though as a side-effect, your patch does avoid doing callbacks on submitted
xfers during DMA_TERMINATE_ALL - which may or may not be the right thing
to do.

It is defined that DMA_TERMINATE_ALL does not call the callbacks:

1. int dmaengine_terminate_all(struct dma_chan *chan)

  This causes all activity for the DMA channel to be stopped, and may
  discard data in the DMA FIFO which hasn't been fully transferred.
  No callback functions will be called for any incomplete transfers.

Ok, thanks for the info.

Boojin Kim, please re-write the changelog to state only preventing
callbacks during DMA_TERMINATE_ALL as the reason.

As above, we don't need callback as well start operation in DMA_TERMIANTE_ALL command and her patch just removed them for DMA_TERMINATE_ALL here. So current git message seems to have proper behavior of patch.

Thanks.

Best regards,
Kgene.
--
Kukjin Kim [off-list ref], Senior Engineer,
SW Solution Development Team, Samsung Electronics Co., Ltd.