From: Nícolas F. R. A. Prado nfraprado@collabora.com
[ Upstream commit 788715b5f21c6455264fe00a1779e61bec407fe2 ]
Before proceeding with the probe and enabling frequency scaling for the CPUs, make sure that all supplies feeding the CPUs have probed.
This fixes an issue observed on MT8195-Tomato where if the mediatek-cpufreq-hw driver enabled the hardware (by writing to REG_FREQ_ENABLE) before the SPMI controller driver (spmi-mtk-pmif), behind which lies the big CPU supply, probed the platform would hang shortly after with "rcu: INFO: rcu_preempt detected stalls on CPUs/tasks" being printed in the log.
Fixes: 4855e26bcf4d ("cpufreq: mediatek-hw: Add support for CPUFREQ HW") Signed-off-by: Nícolas F. R. A. Prado nfraprado@collabora.com Reviewed-by: AngeloGioacchino Del Regno angelogioacchino.delregno@collabora.com Reviewed-by: Matthias Brugger matthias.bgg@gmail.com Signed-off-by: Viresh Kumar viresh.kumar@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/cpufreq/mediatek-cpufreq-hw.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/cpufreq/mediatek-cpufreq-hw.c b/drivers/cpufreq/mediatek-cpufreq-hw.c index 212bbca8daf32..42240a7d826da 100644 --- a/drivers/cpufreq/mediatek-cpufreq-hw.c +++ b/drivers/cpufreq/mediatek-cpufreq-hw.c @@ -13,6 +13,7 @@ #include <linux/of.h> #include <linux/of_platform.h> #include <linux/platform_device.h> +#include <linux/regulator/consumer.h> #include <linux/slab.h>
#define LUT_MAX_ENTRIES 32U @@ -296,7 +297,23 @@ static struct cpufreq_driver cpufreq_mtk_hw_driver = { static int mtk_cpufreq_hw_driver_probe(struct platform_device *pdev) { const void *data; - int ret; + int ret, cpu; + struct device *cpu_dev; + struct regulator *cpu_reg; + + /* Make sure that all CPU supplies are available before proceeding. */ + for_each_possible_cpu(cpu) { + cpu_dev = get_cpu_device(cpu); + if (!cpu_dev) + return dev_err_probe(&pdev->dev, -EPROBE_DEFER, + "Failed to get cpu%d device\n", cpu); + + cpu_reg = devm_regulator_get_optional(cpu_dev, "cpu"); + if (IS_ERR(cpu_reg)) + return dev_err_probe(&pdev->dev, PTR_ERR(cpu_reg), + "CPU%d regulator get failed\n", cpu); + } +
data = of_device_get_match_data(&pdev->dev); if (!data)