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

[Dmitry Osipenko]

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 <pgwipe...@gmail.com>
Tested-by: Nicolas Chauvet <kwiz...@gmail.com>
Signed-off-by: Dmitry Osipenko <dig...@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