clk: mediatek: Do a runtime PM get on controllers during probe

mt8183-mfgcfg has a mutual dependency with genpd during the probing
stage, which leads to a deadlock in the following call stack:

CPU0:  genpd_lock --> clk_prepare_lock
genpd_power_off_work_fn()
 genpd_lock()
 generic_pm_domain::power_off()
    clk_unprepare()
      clk_prepare_lock()

CPU1: clk_prepare_lock --> genpd_lock
clk_register()
  __clk_core_init()
    clk_prepare_lock()
    clk_pm_runtime_get()
      genpd_lock()

Do a runtime PM get at the probe function to make sure clk_register()
won't acquire the genpd lock. Instead of only modifying mt8183-mfgcfg,
do this on all mediatek clock controller probings because we don't
believe this would cause any regression.

Verified on MT8183 and MT8192 Chromebooks.

Fixes: acddfc2c261b ("clk: mediatek: Add MT8183 clock support")
Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Link: https://lore.kernel.org/r/20240312115249.3341654-1-treapking@chromium.org
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
index 2e55368dc4d82095b5baceb7b744a9ed4b1350b4..bd37ab4d1a9bb3252ae54a2f3a3d3d241b1daa3a 100644 (file)
--- a/drivers/clk/mediatek/clk-mtk.c
+++ b/drivers/clk/mediatek/clk-mtk.c
@@ -13,6 +13,7 @@
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/slab.h>
 
 #include "clk-mtk.h"
@@ -494,6 +495,16 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
                        return IS_ERR(base) ? PTR_ERR(base) : -ENOMEM;
        }
 
+
+       devm_pm_runtime_enable(&pdev->dev);
+       /*
+        * Do a pm_runtime_resume_and_get() to workaround a possible
+        * deadlock between clk_register() and the genpd framework.
+        */
+       r = pm_runtime_resume_and_get(&pdev->dev);
+       if (r)
+               return r;
+
        /* Calculate how many clk_hw_onecell_data entries to allocate */
        num_clks = mcd->num_clks + mcd->num_composite_clks;
        num_clks += mcd->num_fixed_clks + mcd->num_factor_clks;
@@ -574,6 +585,8 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
                        goto unregister_clks;
        }
 
+       pm_runtime_put(&pdev->dev);
+
        return r;
 
 unregister_clks:
@@ -604,6 +617,8 @@ free_data:
 free_base:
        if (mcd->shared_io && base)
                iounmap(base);
+
+       pm_runtime_put(&pdev->dev);
        return r;
 }