Messages in this thread Patch in this message | | | From | Eugen Hristev <> | Subject | [PATCH] pmdomain: mediatek: fix race condition in power on/power off sequences | Date | Wed, 29 Nov 2023 13:31:20 +0200 |
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It can happen that during the power off sequence for a power domain another power on sequence is started, and it can lead to powering on and off in the same time for the similar power domain. This can happen if parallel probing occurs: one device starts probing, and one power domain is probe deferred, this leads to all power domains being rolled back and powered off, while in the same time another device starts probing and requests powering on the same power domains or similar.
This was encountered on MT8186, when the sequence is : Power on SSUSB Power on SSUSB_P1 Power on DIS -> probe deferred Power off DIS Power off SSUSB_P1 Power off SSUSB
During the sequence of powering off SSUSB, some new similar sequence starts, and during the power on of SSUSB, clocks are enabled. In this case, powering off SSUSB fails from the first sequence, because power off ACK bit check times out (as clocks are powered back on by the second sequence). In consequence, powering it on also times out, and it leads to the whole power domain in a bad state.
To solve this issue, added a mutex that locks the whole power off/power on sequence such that it would never happen that multiple sequences try to enable or disable the same power domain in parallel.
Fixes: 59b644b01cf4 ("soc: mediatek: Add MediaTek SCPSYS power domains") Signed-off-by: Eugen Hristev <eugen.hristev@collabora.com> --- drivers/pmdomain/mediatek/mtk-pm-domains.c | 24 +++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/drivers/pmdomain/mediatek/mtk-pm-domains.c b/drivers/pmdomain/mediatek/mtk-pm-domains.c index d5f0ee05c794..4f136b47e539 100644 --- a/drivers/pmdomain/mediatek/mtk-pm-domains.c +++ b/drivers/pmdomain/mediatek/mtk-pm-domains.c @@ -9,6 +9,7 @@ #include <linux/io.h> #include <linux/iopoll.h> #include <linux/mfd/syscon.h> +#include <linux/mutex.h> #include <linux/of.h> #include <linux/of_clk.h> #include <linux/platform_device.h> @@ -56,6 +57,7 @@ struct scpsys { struct device *dev; struct regmap *base; const struct scpsys_soc_data *soc_data; + struct mutex mutex; struct genpd_onecell_data pd_data; struct generic_pm_domain *domains[]; }; @@ -238,9 +240,13 @@ static int scpsys_power_on(struct generic_pm_domain *genpd) bool tmp; int ret; + mutex_lock(&scpsys->mutex); + ret = scpsys_regulator_enable(pd->supply); - if (ret) + if (ret) { + mutex_unlock(&scpsys->mutex); return ret; + } ret = clk_bulk_prepare_enable(pd->num_clks, pd->clks); if (ret) @@ -291,6 +297,7 @@ static int scpsys_power_on(struct generic_pm_domain *genpd) goto err_enable_bus_protect; } + mutex_unlock(&scpsys->mutex); return 0; err_enable_bus_protect: @@ -305,6 +312,7 @@ static int scpsys_power_on(struct generic_pm_domain *genpd) clk_bulk_disable_unprepare(pd->num_clks, pd->clks); err_reg: scpsys_regulator_disable(pd->supply); + mutex_unlock(&scpsys->mutex); return ret; } @@ -315,13 +323,15 @@ static int scpsys_power_off(struct generic_pm_domain *genpd) bool tmp; int ret; + mutex_lock(&scpsys->mutex); + ret = scpsys_bus_protect_enable(pd); if (ret < 0) - return ret; + goto err_mutex_unlock; ret = scpsys_sram_disable(pd); if (ret < 0) - return ret; + goto err_mutex_unlock; if (pd->data->ext_buck_iso_offs && MTK_SCPD_CAPS(pd, MTK_SCPD_EXT_BUCK_ISO)) regmap_set_bits(scpsys->base, pd->data->ext_buck_iso_offs, @@ -340,13 +350,15 @@ static int scpsys_power_off(struct generic_pm_domain *genpd) ret = readx_poll_timeout(scpsys_domain_is_on, pd, tmp, !tmp, MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT); if (ret < 0) - return ret; + goto err_mutex_unlock; clk_bulk_disable_unprepare(pd->num_clks, pd->clks); scpsys_regulator_disable(pd->supply); - return 0; +err_mutex_unlock: + mutex_unlock(&scpsys->mutex); + return ret; } static struct @@ -700,6 +712,8 @@ static int scpsys_probe(struct platform_device *pdev) return PTR_ERR(scpsys->base); } + mutex_init(&scpsys->mutex); + ret = -ENODEV; for_each_available_child_of_node(np, node) { struct generic_pm_domain *domain; -- 2.34.1
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