DMAC fixes

- Backport RCAR DMAC fixes from upstream
- Reeneable DMA for SCIF0 on R8A7797

1 files changed, 108 insertions, 0 deletions

diff --git a/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0081-dmaengine-rcar-dmac-use-TCRB-instead-of-TCR-for-resi.patch b/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0081-dmaengine-rcar-dmac-use-TCRB-instead-of-TCR-for-resi.patch
new file mode 100644
index 0000000..c9bfdfb
--- /dev/null
+++ b/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0081-dmaengine-rcar-dmac-use-TCRB-instead-of-TCR-for-resi.patch
@@ -0,0 +1,108 @@
+From 73a47bd0da668c99f04e9076f2b02101a5b2749b Mon Sep 17 00:00:00 2001
+From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
+Date: Fri, 17 Nov 2017 02:09:32 +0000
+Subject: [PATCH 2/2] dmaengine: rcar-dmac: use TCRB instead of TCR for residue
+
+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 PulseAudio 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.
+
+However, because DMAC is buffering data until it can be transferable
+size, TCRB might not be updated.
+For example, if consumer doesn't know how much data can be received,
+it requests enough size to DMAC. But in reality, it might receive very
+few data. In such case, DMAC just buffered it until transferable size,
+and no TCRB updated.
+
+In such case, this buffered data will be transferred if CHCR::DE bit was
+cleared, and this is happen if rcar_dmac_chan_halt(). In other word, it
+happen when consumer called dmaengine_terminate_all().
+
+Because of this behavior, it need to flush buffered data when it returns
+"residue" (= dmaengine_tx_status()).
+Otherwise, consumer might calculate wrong things if it called
+dmaengine_tx_status() and dmaengine_terminate_all() consecutively.
+
+Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
+Tested-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
+Tested-by: Ryo Kodama <ryo.kodama.vz@renesas.com>
+Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
+Signed-off-by: Vinod Koul <vinod.koul@intel.com>
+---
+ drivers/dma/sh/rcar-dmac.c | 22 +++++++++++++++++++++-
+ 1 file changed, 21 insertions(+), 1 deletion(-)
+
+diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
+index c99fd0f..3bbd11d 100644
+--- a/drivers/dma/sh/rcar-dmac.c
++++ b/drivers/dma/sh/rcar-dmac.c
+@@ -761,6 +761,23 @@ static void rcar_dmac_chcr_de_barrier(struct rcar_dmac_chan *chan)
+ 	dev_err(chan->chan.device->dev, "CHCR DE check error\n");
+ }
+ 
++static void rcar_dmac_sync_tcr(struct rcar_dmac_chan *chan)
++{
++	u32 chcr = rcar_dmac_chan_read(chan, RCAR_DMACHCR);
++
++	if (!(chcr & RCAR_DMACHCR_DE))
++		return;
++
++	/* set DE=0 and flush remaining data */
++	rcar_dmac_chan_write(chan, RCAR_DMACHCR, (chcr & ~RCAR_DMACHCR_DE));
++
++	/* make sure all remaining data was flushed */
++	rcar_dmac_chcr_de_barrier(chan);
++
++	/* back DE */
++	rcar_dmac_chan_write(chan, RCAR_DMACHCR, chcr);
++}
++
+ static void rcar_dmac_chan_halt(struct rcar_dmac_chan *chan)
+ {
+ 	u32 chcr = rcar_dmac_chan_read(chan, RCAR_DMACHCR);
+@@ -1329,8 +1346,11 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan,
+ 		residue += chunk->size;
+ 	}
+ 
++	if (desc->direction == DMA_DEV_TO_MEM)
++		rcar_dmac_sync_tcr(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;
+ }
+-- 
+1.9.1
+