[PATCH] mvebu: 5.10: fix DVFS caused random boot crashes

[Robert Marko]

5.10.37 introduced a lot of DVFS changes for Armada 37xx from 5.13 kernel.

Unfortunately commit:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/cpufreq/armada-37xx-cpufreq.c?h=v5.10.37&id=a13b110e7c9e0dc2edcc7a19d4255fc88abd83cc

This patch actually corrects the things so that 1 or 1.2GHz models would actually get scaled to their native frequency.

However, due to a AVS setting voltages too low this will cause random crashes on 1.2GHz models.

So, until a new safe for everybody voltage is agreed on
lets revert the patch.

Fixes: d337731 ("kernel: bump 5.10 to 5.10.37")
Signed-off-by: Robert Marko <robert.marko at sartura.hr>
---
 ...rmada-37xx-Fix-setting-TBG-parent-fo.patch | 101 ++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 target/linux/mvebu/patches-5.10/803-Revert-cpufreq-armada-37xx-Fix-setting-TBG-parent-fo.patch

diff --git a/target/linux/mvebu/patches-5.10/803-Revert-cpufreq-armada-37xx-Fix-setting-TBG-parent-fo.patch b/target/linux/mvebu/patches-5.10/803-Revert-cpufreq-armada-37xx-Fix-setting-TBG-parent-fo.patch
new file mode 100644
index 0000000000..1a44d89ac9
--- /dev/null
+++ b/target/linux/mvebu/patches-5.10/803-Revert-cpufreq-armada-37xx-Fix-setting-TBG-parent-fo.patch
@@ -0,0 +1,101 @@
+From 2dd652976b099f4234fcb8812a2d504bb78f5a24 Mon Sep 17 00:00:00 2001
+From: Robert Marko <robert.marko at sartura.hr>
+Date: Tue, 18 May 2021 13:24:30 +0200
+Subject: [PATCH] Revert "cpufreq: armada-37xx: Fix setting TBG parent for load
+ levels"
+
+This reverts commit a13b110e7c9e0dc2edcc7a19d4255fc88abd83cc.
+
+This commit broke Espressobin Ultra boards with weird and random
+kernel crashes during booting.
+
+Signed-off-by: Robert Marko <robert.marko at sartura.hr>
+---
+ drivers/cpufreq/armada-37xx-cpufreq.c | 35 +++++++++------------------
+ 1 file changed, 12 insertions(+), 23 deletions(-)
+
+--- a/drivers/cpufreq/armada-37xx-cpufreq.c
++++ b/drivers/cpufreq/armada-37xx-cpufreq.c
+@@ -25,10 +25,6 @@
+ 
+ #include "cpufreq-dt.h"
+ 
+-/* Clk register set */
+-#define ARMADA_37XX_CLK_TBG_SEL		0
+-#define ARMADA_37XX_CLK_TBG_SEL_CPU_OFF	22
+-
+ /* Power management in North Bridge register set */
+ #define ARMADA_37XX_NB_L0L1	0x18
+ #define ARMADA_37XX_NB_L2L3	0x1C
+@@ -126,15 +122,10 @@ static struct armada_37xx_dvfs *armada_3
+  * will be configured then the DVFS will be enabled.
+  */
+ static void __init armada37xx_cpufreq_dvfs_setup(struct regmap *base,
+-						 struct regmap *clk_base, u8 *divider)
++						 struct clk *clk, u8 *divider)
+ {
+-	u32 cpu_tbg_sel;
+ 	int load_lvl;
+-
+-	/* Determine to which TBG clock is CPU connected */
+-	regmap_read(clk_base, ARMADA_37XX_CLK_TBG_SEL, &cpu_tbg_sel);
+-	cpu_tbg_sel >>= ARMADA_37XX_CLK_TBG_SEL_CPU_OFF;
+-	cpu_tbg_sel &= ARMADA_37XX_NB_TBG_SEL_MASK;
++	struct clk *parent;
+ 
+ 	for (load_lvl = 0; load_lvl < LOAD_LEVEL_NR; load_lvl++) {
+ 		unsigned int reg, mask, val, offset = 0;
+@@ -153,11 +144,6 @@ static void __init armada37xx_cpufreq_dv
+ 		mask = (ARMADA_37XX_NB_CLK_SEL_MASK
+ 			<< ARMADA_37XX_NB_CLK_SEL_OFF);
+ 
+-		/* Set TBG index, for all levels we use the same TBG */
+-		val = cpu_tbg_sel << ARMADA_37XX_NB_TBG_SEL_OFF;
+-		mask = (ARMADA_37XX_NB_TBG_SEL_MASK
+-			<< ARMADA_37XX_NB_TBG_SEL_OFF);
+-
+ 		/*
+ 		 * Set cpu divider based on the pre-computed array in
+ 		 * order to have balanced step.
+@@ -176,6 +162,14 @@ static void __init armada37xx_cpufreq_dv
+ 
+ 		regmap_update_bits(base, reg, mask, val);
+ 	}
++
++	/*
++	 * Set cpu clock source, for all the level we keep the same
++	 * clock source that the one already configured. For this one
++	 * we need to use the clock framework
++	 */
++	parent = clk_get_parent(clk);
++	clk_set_parent(clk, parent);
+ }
+ 
+ /*
+@@ -401,16 +395,11 @@ static int __init armada37xx_cpufreq_dri
+ 	struct platform_device *pdev;
+ 	unsigned long freq;
+ 	unsigned int cur_frequency, base_frequency;
+-	struct regmap *nb_clk_base, *nb_pm_base, *avs_base;
++	struct regmap *nb_pm_base, *avs_base;
+ 	struct device *cpu_dev;
+ 	int load_lvl, ret;
+ 	struct clk *clk, *parent;
+ 
+-	nb_clk_base =
+-		syscon_regmap_lookup_by_compatible("marvell,armada-3700-periph-clock-nb");
+-	if (IS_ERR(nb_clk_base))
+-		return -ENODEV;
+-
+ 	nb_pm_base =
+ 		syscon_regmap_lookup_by_compatible("marvell,armada-3700-nb-pm");
+ 
+@@ -487,7 +476,7 @@ static int __init armada37xx_cpufreq_dri
+ 	armada37xx_cpufreq_avs_configure(avs_base, dvfs);
+ 	armada37xx_cpufreq_avs_setup(avs_base, dvfs);
+ 
+-	armada37xx_cpufreq_dvfs_setup(nb_pm_base, nb_clk_base, dvfs->divider);
++	armada37xx_cpufreq_dvfs_setup(nb_pm_base, clk, dvfs->divider);
+ 	clk_put(clk);
+ 
+ 	for (load_lvl = ARMADA_37XX_DVFS_LOAD_0; load_lvl < LOAD_LEVEL_NR;
-- 
2.31.1