linux-kernel - [PATCH] PM / devfreq: exynos-bus: Suspend all devices on system shutdown

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Date:   Thu, 21 Mar 2019 10:01:10 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Lukasz Luba <l.luba@...tner.samsung.com>,
        Markus Reichl <m.reichl@...etechno.de>
Subject: [PATCH] PM / devfreq: exynos-bus: Suspend all devices on system
 shutdown

Force all Exynos buses to safe operation points before doing the system
reboot operation. There are board on which some aggressive power saving
operation points are behind the capabilities of the bootloader to properly
reset the hardware and boot the board. This way one can avoid board crash
early after reboot.

This fixes reboot issue on OdroidU3 board both with eMMC and SD boot.

Reported-by: Markus Reichl <m.reichl@...etechno.de>
Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
---
This is an alternative to https://patchwork.kernel.org/patch/10781433/
limited only to Exynos-bus driver.
---
 drivers/devfreq/exynos-bus.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
index c25658b26598..486cc5b422f1 100644
--- a/drivers/devfreq/exynos-bus.c
+++ b/drivers/devfreq/exynos-bus.c
@@ -514,6 +514,13 @@ static int exynos_bus_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static void exynos_bus_shutdown(struct platform_device *pdev)
+{
+	struct exynos_bus *bus = dev_get_drvdata(&pdev->dev);
+
+	devfreq_suspend_device(bus->devfreq);
+}
+
 #ifdef CONFIG_PM_SLEEP
 static int exynos_bus_resume(struct device *dev)
 {
@@ -556,6 +563,7 @@ MODULE_DEVICE_TABLE(of, exynos_bus_of_match);
 
 static struct platform_driver exynos_bus_platdrv = {
 	.probe		= exynos_bus_probe,
+	.shutdown	= exynos_bus_shutdown,
 	.driver = {
 		.name	= "exynos-bus",
 		.pm	= &exynos_bus_pm,
-- 
2.17.1