27.06.2019 22:47, Dmitry Osipenko пишет: > Tegra's APB DMA engine updates words counter after each transferred burst > of data, hence it can report transfer's residual with more fidelity which > may be required in cases like audio playback. In particular this fixes > audio stuttering during playback in a chromium web browser. The patch is > based on the original work that was made by Ben Dooks and a patch from > downstream kernel. It was tested on Tegra20 and Tegra30 devices. > > Link: https://lore.kernel.org/lkml/20190424162348.23692-1-ben.dooks@xxxxxxxxxxxxxxx/ > Link: https://nv-tegra.nvidia.com/gitweb/?p=linux-4.4.git;a=commit;h=c7bba40c6846fbf3eaad35c4472dcc7d8bbc02e5 > Inspired-by: Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx> > Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx> > --- > > Changelog: > > v3: Added workaround for a hardware design shortcoming that results > in a words counter wraparound before end-of-transfer bit is set > in a cyclic mode. > > v2: Addressed review comments made by Jon Hunter to v1. We won't try > to get words count if dma_desc is on free list as it will result > in a NULL dereference because this case wasn't handled properly. > > The residual value is now updated properly, avoiding potential > integer overflow by adding the "bytes" to the "bytes_transferred" > instead of the subtraction. Is there still any chance to get this into 5.3? Will be very nice! Jon / Vinod ?
