Hi Greg, On 26/02/2017 at 11:22:46 +0100, Greg KH wrote: > On Sat, Feb 25, 2017 at 06:49:56PM -0300, Fabio Estevam wrote: > > From: Nandor Han <nandor.han@xxxxxx> > > > > commit 85f57752b33cf12f1d583f0c10b752292de00abe upstream. > > > > The residue calculation was taking in consideration that dma > > transaction status will be always retrieved in the dma callback > > used to inform that dma transfer is complete. However this is not > > the case for all subsystems that use dma. Some subsystems use a > > timer to check the dma status periodically. > > > > Therefore the calculation was updated and residue is calculated > > accordingly by a) update the residue calculation taking in > > consideration the last used buffer index by using *buf_ptail* variable > > and b) chn_real_count (number of bytes transferred) is initialized to > > zero, when dma channel is created, to avoid using an uninitialized > > value in residue calculation when dma status is checked without > > waiting dma complete event. > > > > Cc: <stable@xxxxxxxxxxxxxxx> # 4.9.x > > Signed-off-by: Nandor Han <nandor.han@xxxxxx> > > Acked-by: Peter Senna Tschudin <peter.senna@xxxxxxxxxxxxx> > > Tested-by: Peter Senna Tschudin <peter.senna@xxxxxxxxxxxxx> > > Tested-by: Marek Vasut <marex@xxxxxxx> > > Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxx> > > --- > > drivers/dma/imx-sdma.c | 13 +++++++++---- > > 1 file changed, 9 insertions(+), 4 deletions(-) > > So you want this in the 4.9-stable tree? Why? Can we get an ack from > the maintainer and developers of the patch? And why didn't you sign off > on it as well? > Yes, this solves a real issue, particularly seen (well, heard) when playing audio. Interesting part of the thread starts here: http://lists.infradead.org/pipermail/linux-arm-kernel/2017-February/488393.html -- Alexandre Belloni, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com