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cpufreq: armada-37xx: forbid cpufreq for 1.2 GHz variant

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[ Upstream commit 484f2b7c61 ]

The 1.2 GHz variant of the Armada 3720 SOC is unstable with DVFS: when
the SOC boots, the WTMI firmware sets clocks and AVS values that work
correctly with 1.2 GHz CPU frequency, but random crashes occur once
cpufreq driver starts scaling.

We do not know currently what is the reason:
- it may be that the voltage value for L0 for 1.2 GHz variant provided
  by the vendor in the OTP is simply incorrect when scaling is used,
- it may be that some delay is needed somewhere,
- it may be something else.

The most sane solution now seems to be to simply forbid the cpufreq
driver on 1.2 GHz variant.

Signed-off-by: Marek Behún <kabel@kernel.org>
Fixes: 92ce45fb87 ("cpufreq: Add DVFS support for Armada 37xx")
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Marek Behún 2021-07-01 00:56:01 +02:00 committed by Sasha Levin
parent 5e2d55bceb
commit 16a4777a05
1 changed files with 5 additions and 1 deletions
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6
drivers/cpufreq/armada-37xx-cpufreq.c
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@ -102,7 +102,11 @@ struct armada_37xx_dvfs {
};
static struct armada_37xx_dvfs armada_37xx_dvfs[] = {
{.cpu_freq_max = 1200*1000*1000, .divider = {1, 2, 4, 6} },
/*
* The cpufreq scaling for 1.2 GHz variant of the SOC is currently
* unstable because we do not know how to configure it properly.
*/
/* {.cpu_freq_max = 1200*1000*1000, .divider = {1, 2, 4, 6} }, */
{.cpu_freq_max = 1000*1000*1000, .divider = {1, 2, 4, 5} },
{.cpu_freq_max = 800*1000*1000, .divider = {1, 2, 3, 4} },
{.cpu_freq_max = 600*1000*1000, .divider = {2, 4, 5, 6} },