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* [PATCH] cpufreq: armada-37xx: forbid cpufreq for 1.2 GHz variant
@ 2021-06-30 13:59 Marek Behún
  2021-06-30 14:02 ` Marek Behún
                   ` (2 more replies)
  0 siblings, 3 replies; 23+ messages in thread
From: Marek Behún @ 2021-06-30 13:59 UTC (permalink / raw)
  To: Viresh Kumar, Gregory CLEMENT
  Cc: Robert Marko, Pali Rohár, Tomasz Maciej Nowak,
	Anders Trier Olesen, Philip Soares, linux-pm,
	Sebastian Hesselbarth, linux-arm-kernel, Konstantin Porotchkin,
	nnet, Nadav Haklai, Marek Behún, Marek Behún

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.iorg>
Fixes: 92ce45fb875d ("cpufreq: Add DVFS support for Armada 37xx")
---
If someone from Marvell could look into this, it would be great since
basically 1.2 GHz variant cannot scale, which is a feature that was
claimed to be supported by the SOC.
---
 drivers/cpufreq/armada-37xx-cpufreq.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/cpufreq/armada-37xx-cpufreq.c b/drivers/cpufreq/armada-37xx-cpufreq.c
index 3fc98a3ffd91..1ef3dde9a40b 100644
--- a/drivers/cpufreq/armada-37xx-cpufreq.c
+++ b/drivers/cpufreq/armada-37xx-cpufreq.c
@@ -104,7 +104,13 @@ struct armada_37xx_dvfs {
 };
 
 static struct armada_37xx_dvfs armada_37xx_dvfs[] = {
+#if 0
+	/*
+	 * 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} },
+#endif
 	{.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} },
-- 
2.31.1


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^ permalink raw reply related	[flat|nested] 23+ messages in thread

end of thread, other threads:[~2022-08-25 22:03 UTC | newest]

Thread overview: 23+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-06-30 13:59 [PATCH] cpufreq: armada-37xx: forbid cpufreq for 1.2 GHz variant Marek Behún
2021-06-30 14:02 ` Marek Behún
2021-06-30 15:22 ` Andrew Lunn
2021-06-30 22:56 ` [PATCH v2] " Marek Behún
2021-07-01  2:05   ` Viresh Kumar
2021-07-02 16:30   ` Pali Rohár
2021-07-08 14:34     ` Pali Rohár
2021-07-15 19:33       ` Pali Rohár
2021-08-08 19:30         ` Pali Rohár
2021-08-09  4:02           ` Viresh Kumar
2022-08-01 12:36           ` Pali Rohár
2022-08-01 14:01             ` [EXT] " Elad Nachman
2022-08-01 14:12               ` Pali Rohár
2022-08-01 14:15                 ` Elad Nachman
2022-08-01 17:56                   ` Pali Rohár
     [not found]                     ` <BN9PR18MB42518C761E574D862D30CDA7DB9A9@BN9PR18MB4251.namprd18.prod.outlook.com>
2022-08-02 16:42                       ` Robert Marko
2022-08-02 16:52                         ` Elad Nachman
2022-08-02 16:56                           ` Robert Marko
2022-08-02 17:17                             ` Pali Rohár
2022-08-17  9:40                               ` Robert Marko
2022-08-17 23:10                                 ` Pali Rohár
2022-08-18  8:14                                   ` Robert Marko
2022-08-25 21:49                                     ` Pali Rohár

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