linux-kernel - [PATCH 20/22] mips: csrc-r4k: Decrease r4k-clocksource rating if CPU

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Date:   Fri, 6 Mar 2020 15:47:03 +0300
From:   <Sergey.Semin@...kalelectronics.ru>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>
CC:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Paul Burton <paulburton@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        <linux-mips@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 20/22] mips: csrc-r4k: Decrease r4k-clocksource rating if CPU_FREQ enabled

From: Serge Semin <Sergey.Semin@...kalelectronics.ru>

Commit 07d69579e7fe ("MIPS: Don't register r4k sched clock when
CPUFREQ enabled") disabled the r4k-clock usage for scheduler ticks
counting due to the scheduler being non-tolerant for unstable
clocks sources. For the same reason the clock should be used
in the system clocksource framework only as a last resort if CPU
frequency may change.

Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
Signed-off-by: Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: Paul Burton <paulburton@...nel.org>
Cc: Ralf Baechle <ralf@...ux-mips.org>
---
 arch/mips/kernel/csrc-r4k.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/mips/kernel/csrc-r4k.c b/arch/mips/kernel/csrc-r4k.c
index eed099f35bf1..78ffc105226c 100644
--- a/arch/mips/kernel/csrc-r4k.c
+++ b/arch/mips/kernel/csrc-r4k.c
@@ -71,7 +71,11 @@ int __init init_r4k_clocksource(void)
 		return -ENXIO;
 
 	/* Calculate a somewhat reasonable rating value */
+#ifndef CONFIG_CPU_FREQ
 	clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
+#else
+	clocksource_mips.rating = 99;
+#endif
 
 	/*
 	 * R2 onwards makes the count accessible to user mode so it can be used
-- 
2.25.1