[PATCH v2 5/5] ASoC: tegra: ahub: Reset hardware properly

[Dmitry Osipenko <digetx@gmail.com>]

Assert hardware reset before clocks are enabled and then de-assert it
after clocks are enabled. This brings hardware into a predictable state
and removes relying on implicit de-assertion of resets which is done by
the clk driver.

Tested-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 sound/soc/tegra/tegra30_ahub.c | 43 ++++++++++++++++++++--------------
 sound/soc/tegra/tegra30_ahub.h |  1 +
 2 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/sound/soc/tegra/tegra30_ahub.c b/sound/soc/tegra/tegra30_ahub.c
index 37a847569a40..df4ca2b35566 100644
--- a/sound/soc/tegra/tegra30_ahub.c
+++ b/sound/soc/tegra/tegra30_ahub.c
@@ -65,12 +65,32 @@ static int tegra30_ahub_runtime_resume(struct device *dev)
 {
 	int ret;
 
+	ret = reset_control_assert(ahub->reset);
+	if (ret)
+		return ret;
+
 	ret = clk_bulk_prepare_enable(ahub->nclocks, ahub->clocks);
 	if (ret)
 		return ret;
 
+	ret = reset_control_reset(ahub->reset);
+	if (ret) {
+		clk_bulk_disable_unprepare(ahub->nclocks, ahub->clocks);
+		return ret;
+	}
+
 	regcache_cache_only(ahub->regmap_apbif, false);
 	regcache_cache_only(ahub->regmap_ahub, false);
+	regcache_mark_dirty(ahub->regmap_apbif);
+	regcache_mark_dirty(ahub->regmap_ahub);
+
+	ret = regcache_sync(ahub->regmap_apbif);
+	if (ret)
+		return ret;
+
+	ret = regcache_sync(ahub->regmap_ahub);
+	if (ret)
+		return ret;
 
 	return 0;
 }
@@ -462,7 +482,6 @@ static int tegra30_ahub_probe(struct platform_device *pdev)
 {
 	const struct of_device_id *match;
 	const struct tegra30_ahub_soc_data *soc_data;
-	struct reset_control *rst;
 	struct resource *res0;
 	void __iomem *regs_apbif, *regs_ahub;
 	int ret = 0;
@@ -475,22 +494,6 @@ static int tegra30_ahub_probe(struct platform_device *pdev)
 		return -EINVAL;
 	soc_data = match->data;
 
-	/*
-	 * The AHUB hosts a register bus: the "configlink". For this to
-	 * operate correctly, all devices on this bus must be out of reset.
-	 * Ensure that here.
-	 */
-	rst = of_reset_control_array_get_exclusive(pdev->dev.of_node);
-	if (IS_ERR(rst)) {
-		dev_err(&pdev->dev, "Can't get reset: %pe\n", rst);
-		return PTR_ERR(rst);
-	}
-
-	ret = reset_control_deassert(rst);
-	reset_control_put(rst);
-	if (ret)
-		return ret;
-
 	ahub = devm_kzalloc(&pdev->dev, sizeof(struct tegra30_ahub),
 			    GFP_KERNEL);
 	if (!ahub)
@@ -507,6 +510,12 @@ static int tegra30_ahub_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	ahub->reset = devm_reset_control_array_get_exclusive(&pdev->dev);
+	if (IS_ERR(ahub->reset)) {
+		dev_err(&pdev->dev, "Can't get reset: %pe\n", ahub->reset);
+		return PTR_ERR(ahub->reset);
+	}
+
 	res0 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	regs_apbif = devm_ioremap_resource(&pdev->dev, res0);
 	if (IS_ERR(regs_apbif))
diff --git a/sound/soc/tegra/tegra30_ahub.h b/sound/soc/tegra/tegra30_ahub.h
index 063aed5037d7..ceb056575e98 100644
--- a/sound/soc/tegra/tegra30_ahub.h
+++ b/sound/soc/tegra/tegra30_ahub.h
@@ -510,6 +510,7 @@ struct tegra30_ahub_soc_data {
 struct tegra30_ahub {
 	const struct tegra30_ahub_soc_data *soc_data;
 	struct device *dev;
+	struct reset_control *reset;
 	struct clk_bulk_data clocks[2];
 	unsigned int nclocks;
 	resource_size_t apbif_addr;
-- 
2.29.2