| From ab999a146f84d971ff425c35358e4e833463c1b0 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Thu, 8 Apr 2021 13:42:17 +0200 |
| Subject: cpufreq: armada-37xx: Fix the AVS value for load L1 |
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| Content-Type: text/plain; charset=UTF-8 |
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| |
| From: Pali Rohár <pali@kernel.org> |
| |
| [ Upstream commit d118ac2062b5b8331c8768ac81e016617e0996ee ] |
| |
| The original CPU voltage value for load L1 is too low for Armada 37xx SoC |
| when base CPU frequency is 1000 or 1200 MHz. It leads to instabilities |
| where CPU gets stuck soon after dynamic voltage scaling from load L1 to L0. |
| |
| Update the CPU voltage value for load L1 accordingly when base frequency is |
| 1000 or 1200 MHz. The minimal L1 value for base CPU frequency 1000 MHz is |
| updated from the original 1.05V to 1.108V and for 1200 MHz is updated to |
| 1.155V. This minimal L1 value is used only in the case when it is lower |
| than value for L0. |
| |
| This change fixes CPU instability issues on 1 GHz and 1.2 GHz variants of |
| Espressobin and 1 GHz Turris Mox. |
| |
| Marvell previously for 1 GHz variant of Espressobin provided a patch [1] |
| suitable only for their Marvell Linux kernel 4.4 fork which workarounded |
| this issue. Patch forced CPU voltage value to 1.108V in all loads. But |
| such change does not fix CPU instability issues on 1.2 GHz variants of |
| Armada 3720 SoC. |
| |
| During testing we come to the conclusion that using 1.108V as minimal |
| value for L1 load makes 1 GHz variants of Espressobin and Turris Mox boards |
| stable. And similarly 1.155V for 1.2 GHz variant of Espressobin. |
| |
| These two values 1.108V and 1.155V are documented in Armada 3700 Hardware |
| Specifications as typical initial CPU voltage values. |
| |
| Discussion about this issue is also at the Armbian forum [2]. |
| |
| [1] - https://github.com/MarvellEmbeddedProcessors/linux-marvell/commit/dc33b62c90696afb6adc7dbcc4ebbd48bedec269 |
| [2] - https://forum.armbian.com/topic/10429-how-to-make-espressobin-v7-stable/ |
| |
| Signed-off-by: Pali Rohár <pali@kernel.org> |
| Acked-by: Gregory CLEMENT <gregory.clement@bootlin.com> |
| Tested-by: Tomasz Maciej Nowak <tmn505@gmail.com> |
| Tested-by: Anders Trier Olesen <anders.trier.olesen@gmail.com> |
| Tested-by: Philip Soares <philips@netisense.com> |
| Fixes: 1c3528232f4b ("cpufreq: armada-37xx: Add AVS support") |
| Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/cpufreq/armada-37xx-cpufreq.c | 37 +++++++++++++++++++++++++++ |
| 1 file changed, 37 insertions(+) |
| |
| diff --git a/drivers/cpufreq/armada-37xx-cpufreq.c b/drivers/cpufreq/armada-37xx-cpufreq.c |
| index b8dc6c849579..c7683d447b11 100644 |
| --- a/drivers/cpufreq/armada-37xx-cpufreq.c |
| +++ b/drivers/cpufreq/armada-37xx-cpufreq.c |
| @@ -73,6 +73,8 @@ |
| #define LOAD_LEVEL_NR 4 |
| |
| #define MIN_VOLT_MV 1000 |
| +#define MIN_VOLT_MV_FOR_L1_1000MHZ 1108 |
| +#define MIN_VOLT_MV_FOR_L1_1200MHZ 1155 |
| |
| /* AVS value for the corresponding voltage (in mV) */ |
| static int avs_map[] = { |
| @@ -208,6 +210,8 @@ static u32 armada_37xx_avs_val_match(int target_vm) |
| * - L2 & L3 voltage should be about 150mv smaller than L0 voltage. |
| * This function calculates L1 & L2 & L3 AVS values dynamically based |
| * on L0 voltage and fill all AVS values to the AVS value table. |
| + * When base CPU frequency is 1000 or 1200 MHz then there is additional |
| + * minimal avs value for load L1. |
| */ |
| static void __init armada37xx_cpufreq_avs_configure(struct regmap *base, |
| struct armada_37xx_dvfs *dvfs) |
| @@ -239,6 +243,19 @@ static void __init armada37xx_cpufreq_avs_configure(struct regmap *base, |
| for (load_level = 1; load_level < LOAD_LEVEL_NR; load_level++) |
| dvfs->avs[load_level] = avs_min; |
| |
| + /* |
| + * Set the avs values for load L0 and L1 when base CPU frequency |
| + * is 1000/1200 MHz to its typical initial values according to |
| + * the Armada 3700 Hardware Specifications. |
| + */ |
| + if (dvfs->cpu_freq_max >= 1000*1000*1000) { |
| + if (dvfs->cpu_freq_max >= 1200*1000*1000) |
| + avs_min = armada_37xx_avs_val_match(MIN_VOLT_MV_FOR_L1_1200MHZ); |
| + else |
| + avs_min = armada_37xx_avs_val_match(MIN_VOLT_MV_FOR_L1_1000MHZ); |
| + dvfs->avs[0] = dvfs->avs[1] = avs_min; |
| + } |
| + |
| return; |
| } |
| |
| @@ -258,6 +275,26 @@ static void __init armada37xx_cpufreq_avs_configure(struct regmap *base, |
| target_vm = avs_map[l0_vdd_min] - 150; |
| target_vm = target_vm > MIN_VOLT_MV ? target_vm : MIN_VOLT_MV; |
| dvfs->avs[2] = dvfs->avs[3] = armada_37xx_avs_val_match(target_vm); |
| + |
| + /* |
| + * Fix the avs value for load L1 when base CPU frequency is 1000/1200 MHz, |
| + * otherwise the CPU gets stuck when switching from load L1 to load L0. |
| + * Also ensure that avs value for load L1 is not higher than for L0. |
| + */ |
| + if (dvfs->cpu_freq_max >= 1000*1000*1000) { |
| + u32 avs_min_l1; |
| + |
| + if (dvfs->cpu_freq_max >= 1200*1000*1000) |
| + avs_min_l1 = armada_37xx_avs_val_match(MIN_VOLT_MV_FOR_L1_1200MHZ); |
| + else |
| + avs_min_l1 = armada_37xx_avs_val_match(MIN_VOLT_MV_FOR_L1_1000MHZ); |
| + |
| + if (avs_min_l1 > dvfs->avs[0]) |
| + avs_min_l1 = dvfs->avs[0]; |
| + |
| + if (dvfs->avs[1] < avs_min_l1) |
| + dvfs->avs[1] = avs_min_l1; |
| + } |
| } |
| |
| static void __init armada37xx_cpufreq_avs_setup(struct regmap *base, |
| -- |
| 2.30.2 |
| |