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

[Kukjin Kim]

Jassi Brar wrote:
> 
> 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.

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 <kgene.kim at samsung.com>, Senior Engineer,
SW Solution Development Team, Samsung Electronics Co., Ltd.