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

[Jassi Brar]

On 6 September 2011 17:57, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Tue, Sep 06, 2011 at 05:52:19PM +0530, Jassi Brar wrote:
>> On Fri, Sep 2, 2011 at 6:14 AM, Boojin Kim <boojin.kim at samsung.com> wrote:
>> > 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.