Hello,
There is an inconsistency in this code:
/sound/soc/imx/imx-ssi.c: ssi->dma_params_tx.burstsize = 4; /sound/soc/imx/imx-pcm-dma-mx2.c: ssi->dma_params_tx.burstsize = 6;
Datasheet: This sets the field TFWM0 in register SFCSR (SSI_SFCSR_TFWM0): the number of data words needed to set the empty flag (TFE0). Can be set from 1 to 8; FIFO size is 8 words (of 24b). And this is also the DMA burst size.
Which is best depends on the application (the higher the more efficient, but the more risk for a FIFO underrun). I would take 4.
But I guess it should only be set at 1 place, and what is then the best place?
Regards, Jürgen
details:
/sound/soc/imx/imx-ssi.c: ssi->dma_params_tx.burstsize = 4; Set in commit commit 0a93421b6adf8ba127b3eafc4c16e3a14017e2ae Author: Javier Martin javier.martin@vista-silicon.com Date: Tue Mar 1 15:02:06 2011 +0100
ASoC: Fix burstsize and DSP_B format problems in imx-ssi.
When choosing IMX_DMA flag, burtsizes are set to its default value (0) which leads to driver malfunction. Change them to 4.
DSP_B interface needs additional flag to match DSP_B formats as described in several codecs as wm8741 and aic3205.
Signed-off-by: Javier Martin javier.martin@vista-silicon.com Acked-by: Liam Girdwood lrg@slimlogic.co.uk Signed-off-by: Mark Brown broonie@opensource.wolfsonmicro.com
Index in diff: diff --git a/sound/soc/imx/imx-ssi.c b/sound/soc/imx/imx-ssi.c index 30894ea..bc92ec6 100644
/sound/soc/imx/imx-pcm-dma-mx2.c: ssi->dma_params_tx.burstsize = 6; Set in commit commit 2c4cf17a52f04fbe929977252d5b8ab81d2c6e9b Author: Wolfram Sang w.sang@pengutronix.de Date: Fri Mar 25 16:51:44 2011 +0100
ASoC: imx: set watermarks for mx2-dma
They got accidently removed by f0fba2a (ASoC: multi-component - ASoC Multi-Component Support). Reintroduce them and get rid of the superfluous defines because the fiq-driver has its own hardcoded values.
Signed-off-by: Wolfram Sang w.sang@pengutronix.de Acked-by: Liam Girdwood lrg@ti.com Signed-off-by: Mark Brown broonie@opensource.wolfsonmicro.com Cc: stable@kernel.org
Index in diff: diff --git a/sound/soc/imx/imx-pcm-dma-mx2.c b/sound/soc/imx/imx-pcm-dma-mx2.c index 671ef8d..b2ed764 100644