Revert "mvebu: 5.4 fix DVFS caused random boot crashes"

Based on the discussion on the mailing list [1], the patch which was
reverted, it reverts only one patch without the subsequent ones.

This leads to the SoC scaling issue not using a CPU parent clock, but
it uses DDR clock. This is done for all variants, and it's wrong because
commits (hacks) that were using the DDR clock are no longer in the mainline kernel.

If someone has stability issues on 1.2 GHz, it should not affect all
routers (1 GHz, 800 MHz) and it should be rather consulted with guys, who are trying to
improve the situation in the kernel and not making the situation worse.

There are two solutions in cases of instability:
a) disable cpufreq
b) underclock it up to 1 GHz

This reverts commit 080a0b74e39d159eecf69c468debec42f28bf4d8.

[1] https://lists.openwrt.org/pipermail/openwrt-devel/2021-June/035702.html

CC: Pali Rohár <pali@kernel.org>
Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
(cherry picked from commit 7b868fe04a8961048feec1143e72fe47bde52a12)

diff --git a/target/linux/mvebu/patches-5.4/803-Revert-cpufreq-armada-37xx-Fix-setting-TBG-parent-fo.patch b/target/linux/mvebu/patches-5.4/803-Revert-cpufreq-armada-37xx-Fix-setting-TBG-parent-fo.patch
deleted file mode 100644 (file)
index 65184df..0000000
--- a/target/linux/mvebu/patches-5.4/803-Revert-cpufreq-armada-37xx-Fix-setting-TBG-parent-fo.patch
+++ /dev/null
@@ -1,107 +0,0 @@
-From 35639bac13927d1476398b740b11cbed0ee3ddb2 Mon Sep 17 00:00:00 2001
-From: Robert Marko <robert.marko@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 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.
-
-Signed-off-by: Robert Marko <robert.marko@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;