Patch "clk: mediatek: Do a runtime PM get on controllers during probe" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     clk-mediatek-do-a-runtime-pm-get-on-controllers-duri.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 48e47292742c39b19ee238d3b09443d27a88123d
Author: Pin-yen Lin <treapking@xxxxxxxxxxxx>
Date:   Tue Mar 12 19:51:55 2024 +0800

    clk: mediatek: Do a runtime PM get on controllers during probe
    
    [ Upstream commit 2f7b1d8b5505efb0057cd1ab85fca206063ea4c3 ]
    
    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@xxxxxxxxxxxx>
    
    Link: https://lore.kernel.org/r/20240312115249.3341654-1-treapking@xxxxxxxxxxxx
    Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
    Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
    Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
index 2e55368dc4d82..bd37ab4d1a9bb 100644
--- 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 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
 free_base:
 	if (mcd->shared_io && base)
 		iounmap(base);
+
+	pm_runtime_put(&pdev->dev);
 	return r;
 }