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4b2dc4dbbf
This patch is backported from linux-arm-kernel [1] to improve situation, when
it was reported that 1.2 GHz variant is unstable with DFS.
It waits to be accepted upstream, however, it waits for Marvell people to respond.
[1] https://patchwork.kernel.org/project/linux-arm-kernel/patch/20210630225601.6372-1-kabel@kernel.org/
Fixes: 7b868fe04a ("Revert "mvebu: 5.4 fix DVFS caused random boot crashes"")
Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
40 lines
1.6 KiB
Diff
40 lines
1.6 KiB
Diff
From: =?utf-8?q?Marek_Beh=C3=BAn?= <kabel@kernel.org>
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Subject: [PATCH v2] cpufreq: armada-37xx: forbid cpufreq for 1.2 GHz variant
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Date: Thu, 1 Jul 2021 00:56:01 +0200
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The 1.2 GHz variant of the Armada 3720 SOC is unstable with DVFS: when
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the SOC boots, the WTMI firmware sets clocks and AVS values that work
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correctly with 1.2 GHz CPU frequency, but random crashes occur once
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cpufreq driver starts scaling.
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We do not know currently what is the reason:
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- it may be that the voltage value for L0 for 1.2 GHz variant provided
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by the vendor in the OTP is simply incorrect when scaling is used,
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- it may be that some delay is needed somewhere,
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- it may be something else.
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The most sane solution now seems to be to simply forbid the cpufreq
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driver on 1.2 GHz variant.
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Signed-off-by: Marek Behún <kabel@kernel.org>
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Fixes: 92ce45fb875d ("cpufreq: Add DVFS support for Armada 37xx")
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---
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drivers/cpufreq/armada-37xx-cpufreq.c | 6 +++++-
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1 file changed, 5 insertions(+), 1 deletion(-)
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--- a/drivers/cpufreq/armada-37xx-cpufreq.c
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+++ b/drivers/cpufreq/armada-37xx-cpufreq.c
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@@ -102,7 +102,11 @@ struct armada_37xx_dvfs {
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};
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static struct armada_37xx_dvfs armada_37xx_dvfs[] = {
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- {.cpu_freq_max = 1200*1000*1000, .divider = {1, 2, 4, 6} },
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+ /*
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+ * The cpufreq scaling for 1.2 GHz variant of the SOC is currently
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+ * unstable because we do not know how to configure it properly.
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+ */
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+ /* {.cpu_freq_max = 1200*1000*1000, .divider = {1, 2, 4, 6} }, */
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{.cpu_freq_max = 1000*1000*1000, .divider = {1, 2, 4, 5} },
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{.cpu_freq_max = 800*1000*1000, .divider = {1, 2, 3, 4} },
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{.cpu_freq_max = 600*1000*1000, .divider = {2, 4, 5, 6} },
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