linux-kernel - [PATCH] cpufreq: enable 1200Mhz clock speed for armada-37xx

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Message-ID: <20241125211452.14987-1-ben@bens.haus>
Date: Mon, 25 Nov 2024 13:14:52 -0800
From: bschnei@...il.com
To: "Rafael J . Wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Benjamin Schneider <ben@...s.haus>,
	Pali Rohár <pali@...nel.org>,
	Andrew Lunn <andrew@...n.ch>,
	Gregory CLEMENT <gregory.clement@...tlin.com>
Subject: [PATCH] cpufreq: enable 1200Mhz clock speed for armada-37xx

From: Benjamin Schneider <ben@...s.haus>

This frequency was disabled because of stability problems whose source could
not be accurately identified[1]. After seven months of testing, the evidence
points to an incorrectly configured bootloader as the source of the historical
instability. Testing was performed on two A3720 devices with this frequency
enabled and the ondemand policy in use. Marvell merged[2] changes to their
bootloader source needed to address the stability issue. This driver should
expose this frequency option to users.

[1] https://github.com/torvalds/linux/commit/484f2b7c61b9ae58cc00c5127bcbcd9177af8dfe
[2] https://github.com/MarvellEmbeddedProcessors/mv-ddr-marvell/pull/44

Signed-off-by: Benjamin Schneider <ben@...s.haus>
Reviewed-by: Pali Rohár <pali@...nel.org>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Acked-by: Gregory CLEMENT <gregory.clement@...tlin.com>
---
 drivers/cpufreq/armada-37xx-cpufreq.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/cpufreq/armada-37xx-cpufreq.c b/drivers/cpufreq/armada-37xx-cpufreq.c
index bea41ccabf1f..f28a4435fba7 100644
--- a/drivers/cpufreq/armada-37xx-cpufreq.c
+++ b/drivers/cpufreq/armada-37xx-cpufreq.c
@@ -102,11 +102,7 @@ struct armada_37xx_dvfs {
 };
 
 static struct armada_37xx_dvfs armada_37xx_dvfs[] = {
-	/*
-	 * 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 = 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} },
-- 
2.47.1