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ASoC: meson: axg-tdm-formatter: add reset 

Add the optional reset line handling which is present on the new SoC
families, such as the g12a. Triggering this reset is not critical but
it helps solve a channel shift issue on the g12a.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20190703120749.32341-3-jbrunet@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>
alistair/sunxi64-5.4-dsi
Jerome Brunet 2019-07-03 14:07:49 +02:00 committed by Mark Brown
parent 094380ea2b
commit 751bd5db52
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GPG Key ID: 24D68B725D5487D0
1 changed files with 29 additions and 0 deletions
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29
sound/soc/meson/axg-tdm-formatter.c
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@ -7,6 +7,7 @@
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/regmap.h>
#include <linux/reset.h>
#include <sound/soc.h>
#include "axg-tdm-formatter.h"
@ -20,6 +21,7 @@ struct axg_tdm_formatter {
struct clk *lrclk;
struct clk *sclk_sel;
struct clk *lrclk_sel;
struct reset_control *reset;
bool enabled;
struct regmap *map;
};
@ -75,6 +77,24 @@ static int axg_tdm_formatter_enable(struct axg_tdm_formatter *formatter)
if (formatter->enabled)
return 0;
/*
* On the g12a (and possibly other SoCs), when a stream using
* multiple lanes is restarted, it will sometimes not start
* from the first lane, but randomly from another used one.
* The result is an unexpected and random channel shift.
*
* The hypothesis is that an HW counter is not properly reset
* and the formatter simply starts on the lane it stopped
* before. Unfortunately, there does not seems to be a way to
* reset this through the registers of the block.
*
* However, the g12a has indenpendent reset lines for each audio
* devices. Using this reset before each start solves the issue.
*/
ret = reset_control_reset(formatter->reset);
if (ret)
return ret;
/*
* If sclk is inverted, invert it back and provide the inversion
* required by the formatter
@ -306,6 +326,15 @@ int axg_tdm_formatter_probe(struct platform_device *pdev)
return ret;
}
/* Formatter dedicated reset line */
formatter->reset = reset_control_get_optional_exclusive(dev, NULL);
if (IS_ERR(formatter->reset)) {
ret = PTR_ERR(formatter->reset);
if (ret != -EPROBE_DEFER)
dev_err(dev, "failed to get reset: %d\n", ret);
return ret;
}
return devm_snd_soc_register_component(dev, drv->component_drv,
NULL, 0);
}