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@xxxxxxxxxxxx>
---
sound/soc/meson/axg-tdm-formatter.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/sound/soc/meson/axg-tdm-formatter.c b/sound/soc/meson/axg-tdm-formatter.c
index 0c6cce5c5773..2e498201139f 100644
--- a/sound/soc/meson/axg-tdm-formatter.c
+++ b/sound/soc/meson/axg-tdm-formatter.c
@@ -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);
}
--
2.21.0
