linux-kernel - [tip: timers/core] clocksource: dw_apb_timer: Affiliate of-based timer with any CPU

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Date:   Mon, 01 Jun 2020 13:11:37 -0000
From:   "tip-bot2 for Serge Semin" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Paul Burton <paulburton@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Arnd Bergmann <arnd@...db.de>,
        Rob Herring <robh+dt@...nel.org>, linux-mips@...r.kernel.org,
        linux-rtc@...r.kernel.org, devicetree@...r.kernel.org,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: timers/core] clocksource: dw_apb_timer: Affiliate of-based
 timer with any CPU

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     65e0f876405ef4f0ff25eb1c5ff3e9b536d68805
Gitweb:        https://git.kernel.org/tip/65e0f876405ef4f0ff25eb1c5ff3e9b536d68805
Author:        Serge Semin <Sergey.Semin@...kalelectronics.ru>
AuthorDate:    Thu, 21 May 2020 23:48:14 +03:00
Committer:     Daniel Lezcano <daniel.lezcano@...aro.org>
CommitterDate: Sat, 23 May 2020 00:02:50 +02:00

clocksource: dw_apb_timer: Affiliate of-based timer with any CPU

Currently any DW APB Timer device detected in OF is bound to CPU #0.
Doing so is redundant since DW APB Timer isn't CPU-local timer, but as
having APB interface is normally accessible from any CPU in the system. By
artificially affiliating the DW timer to the very first CPU we may and in
our case will make the clockevent subsystem to decline the more performant
real CPU-local timers selection in favor of in fact non-local and
accessible over a slow bus - DW APB Timers.

Let's not affiliate the of-detected DW APB Timers to any CPU. By doing so
the clockevent framework would prefer to select the real CPU-local timer
instead of DW APB one. Otherwise if there is no other than DW APB device
for clockevents tracking then it will be selected.

Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc: 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>
Cc: Alessandro Zummo <a.zummo@...ertech.it>
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: linux-mips@...r.kernel.org
Cc: linux-rtc@...r.kernel.org
Cc: devicetree@...r.kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Link: https://lore.kernel.org/r/20200521204818.25436-6-Sergey.Semin@baikalelectronics.ru
---
 drivers/clocksource/dw_apb_timer_of.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/dw_apb_timer_of.c b/drivers/clocksource/dw_apb_timer_of.c
index 8c28b12..2db490f 100644
--- a/drivers/clocksource/dw_apb_timer_of.c
+++ b/drivers/clocksource/dw_apb_timer_of.c
@@ -73,7 +73,7 @@ static void __init add_clockevent(struct device_node *event_timer)
 
 	timer_get_base_and_rate(event_timer, &iobase, &rate);
 
-	ced = dw_apb_clockevent_init(0, event_timer->name, 300, iobase, irq,
+	ced = dw_apb_clockevent_init(-1, event_timer->name, 300, iobase, irq,
 				     rate);
 	if (!ced)
 		panic("Unable to initialise clockevent device");