Kuninori Morimoto 73a47bd0da 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 (= 07b7acb51d ("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>		2017-11-29 19:42:57 +05:30
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Kconfig	dmaengine: sh: Use ARCH_RENESAS	2016-02-08 08:48:08 +05:30
Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
rcar-dmac.c	dmaengine: rcar-dmac: use TCRB instead of TCR for residue	2017-11-29 19:42:57 +05:30
shdma-arm.h	dmaengine: shdma: Use defines instead of hardcoded numbers	2014-07-15 18:02:29 +09:00
shdma-base.c	dmaengine: sh_shdma-base: convert callback to helper function	2016-08-08 08:11:43 +05:30
shdma-of.c	dmaengine: Remove .owner field for driver	2014-11-06 11:54:18 +05:30
shdma-r8a73a4.c	dmaengine: shdma: r8a73a4: Make dma_ts_shift[] static	2015-05-25 22:33:07 +05:30
shdma.h	dmaengine: sh: Rework Kconfig and Makefile	2014-07-31 17:15:45 +05:30
shdmac.c	dmaengine: Remove site specific OOM error messages on kzalloc	2016-06-21 21:35:00 +05:30
sudmac.c	dmaengine: Remove site specific OOM error messages on kzalloc	2016-06-21 21:35:00 +05:30
usb-dmac.c	dmaengine: usb-dmac: Fix DMAOR AE bit definition	2017-05-16 09:58:51 +05:30