From: Hiroyuki Yokoyama hiroyuki.yokoyama.vx@renesas.com
[ Upstream commit 847449f23dcbff68234525f90dd53c7c7db18cad ]
SYS/RT/Audio DMAC includes independent data buffers for reading and writing. Therefore, the read transfer counter and write transfer counter have different values. TCR indicates read counter, and TCRB indicates write counter. The relationship is like below.
TCR TCRB [SOURCE] -> [DMAC] -> [SINK]
In the MEM_TO_DEV direction, what really matters is how much data has been written to the device. If the DMA is interrupted between read and write, then, the data doesn't end up in the destination, so shouldn't be counted. TCRB is thus the register we should use in this cases.
In the DEV_TO_MEM direction, the situation is more complex. Both the read and write side are important. What matters from a data consumer point of view is how much data has been written to memory. On the other hand, if the transfer is interrupted between read and write, we'll end up losing data. It can also be important to report.
In the MEM_TO_MEM direction, what matters is of course how much data has been written to memory from data consumer point of view. Here, because read and write have independent data buffers, it will take a while for TCR and TCRB to become equal. Thus we should check TCRB in this case, too.
Thus, all cases we should check TCRB instead of TCR.
Without this patch, Sound Capture has noise after PluseAudio support (= 07b7acb51d2 ("ASoC: rsnd: update pointer more accurate")), because the recorder will use wrong residue counter which indicates transferred from sound device, but in reality the data was not yet put to memory and recorder will record it.
Signed-off-by: Hiroyuki Yokoyama hiroyuki.yokoyama.vx@renesas.com [Kuninori: added detail information in log] Signed-off-by: Kuninori Morimoto kuninori.morimoto.gx@renesas.com Reviewed-by: Geert Uytterhoeven geert+renesas@glider.be Reviewed-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Vinod Koul vinod.koul@intel.com
Signed-off-by: Sasha Levin alexander.levin@verizon.com --- drivers/dma/sh/rcar-dmac.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c index 7820d07e7bee..3e83d02d9ae3 100644 --- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -1180,7 +1180,7 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan, }
/* Add the residue for the current chunk. */ - residue += rcar_dmac_chan_read(chan, RCAR_DMATCR) << desc->xfer_shift; + residue += rcar_dmac_chan_read(chan, RCAR_DMATCRB) << desc->xfer_shift;
return residue; }