[PATCH v3 2/6] ALSA: hda/tegra: Reset hardware

[Dmitry Osipenko <digetx@gmail.com>]

Reset hardware on RPM-resume in order to bring it into a predictable
state.

Tested-by: Peter Geis <pgwipeout@gmail.com> # Ouya T30 audio works
Tested-by: Matt Merhar <mattmerhar@protonmail.com> # Ouya T30 boot-tested
Tested-by: Nicolas Chauvet <kwizart@gmail.com> # TK1 boot-tested
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 sound/pci/hda/hda_tegra.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/sound/pci/hda/hda_tegra.c b/sound/pci/hda/hda_tegra.c
index a25bf7083c28..04dcd4cdfd9e 100644
--- a/sound/pci/hda/hda_tegra.c
+++ b/sound/pci/hda/hda_tegra.c
@@ -17,6 +17,7 @@
 #include <linux/moduleparam.h>
 #include <linux/mutex.h>
 #include <linux/of_device.h>
+#include <linux/reset.h>
 #include <linux/slab.h>
 #include <linux/time.h>
 #include <linux/string.h>
@@ -70,6 +71,7 @@
 struct hda_tegra {
 	struct azx chip;
 	struct device *dev;
+	struct reset_control *reset;
 	struct clk_bulk_data clocks[3];
 	unsigned int nclocks;
 	void __iomem *regs;
@@ -167,6 +169,12 @@ static int __maybe_unused hda_tegra_runtime_resume(struct device *dev)
 	struct hda_tegra *hda = container_of(chip, struct hda_tegra, chip);
 	int rc;
 
+	if (!chip->running) {
+		rc = reset_control_assert(hda->reset);
+		if (rc)
+			return rc;
+	}
+
 	rc = clk_bulk_prepare_enable(hda->nclocks, hda->clocks);
 	if (rc != 0)
 		return rc;
@@ -176,6 +184,12 @@ static int __maybe_unused hda_tegra_runtime_resume(struct device *dev)
 		/* disable controller wake up event*/
 		azx_writew(chip, WAKEEN, azx_readw(chip, WAKEEN) &
 			   ~STATESTS_INT_MASK);
+	} else {
+		usleep_range(10, 100);
+
+		rc = reset_control_deassert(hda->reset);
+		if (rc)
+			return rc;
 	}
 
 	return 0;
@@ -441,6 +455,12 @@ static int hda_tegra_probe(struct platform_device *pdev)
 		return err;
 	}
 
+	hda->reset = devm_reset_control_array_get_exclusive(&pdev->dev);
+	if (IS_ERR(hda->reset)) {
+		err = PTR_ERR(hda->reset);
+		goto out_free;
+	}
+
 	hda->clocks[hda->nclocks++].id = "hda";
 	hda->clocks[hda->nclocks++].id = "hda2hdmi";
 	hda->clocks[hda->nclocks++].id = "hda2codec_2x";
-- 
2.29.2