diff options
Diffstat (limited to 'meta-rcar-gen3/recipes-kernel/linux/linux-renesas/0002-dmaengine-rcar-dmac-use-TCRB-instead-of-TCR-for-resi.patch')
| -rw-r--r-- | meta-rcar-gen3/recipes-kernel/linux/linux-renesas/0002-dmaengine-rcar-dmac-use-TCRB-instead-of-TCR-for-resi.patch | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/meta-rcar-gen3/recipes-kernel/linux/linux-renesas/0002-dmaengine-rcar-dmac-use-TCRB-instead-of-TCR-for-resi.patch b/meta-rcar-gen3/recipes-kernel/linux/linux-renesas/0002-dmaengine-rcar-dmac-use-TCRB-instead-of-TCR-for-resi.patch new file mode 100644 index 0000000..3454dff --- /dev/null +++ b/meta-rcar-gen3/recipes-kernel/linux/linux-renesas/0002-dmaengine-rcar-dmac-use-TCRB-instead-of-TCR-for-resi.patch @@ -0,0 +1,104 @@ +From f5c857fb5913dcb4eea2e213ee69790b6dc127dd Mon Sep 17 00:00:00 2001 +From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> +Date: Mon, 13 Nov 2017 13:34:04 +0900 +Subject: [PATCH 2/3] 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 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. + +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 receaved, +it requests enough size to DMAC. But in reality, it might receave very +few data. In such case, DMAC just buffered it untile transferable size, +and no TCRB updated. + +In such case, this buffered data will be transfered 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> +--- + 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 16ebd5d..9cb85b2 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 fulshed */ ++ 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 + |