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 <[email protected]>
---
v3: https://lore.kernel.org/all/[email protected]/
Changes in v4:
- Remove the need_runtime_pm flag and apply this to all mtk controllers
Changes in v3:
- Update the commit message and the comments before runtime PM call
Changes in v2:
- Fix the order of error handling
- Update the commit message and add a comment before the runtime PM call
drivers/clk/mediatek/clk-mtk.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
index 2e55368dc4d8..bd37ab4d1a9b 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;
}
--
2.44.0.278.ge034bb2e1d-goog
Il 12/03/24 12:51, Pin-yen Lin ha scritto:
> 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 <[email protected]>
>
MT8195 Cherry Tomato - no issues as well.
Tested-by: AngeloGioacchino Del Regno <[email protected]>
Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
Quoting Pin-yen Lin (2024-03-12 04:51:55)
> 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 <[email protected]>
>
> ---
Applied to clk-fixes