linux-kernel - [RFC] platform: detach from PM domains on shutdown

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Date:   Tue, 15 May 2018 17:01:10 +0800
From:   Peng Fan <peng.fan@....com>
To:     rafael.j.wysocki@...el.com
Cc:     ulf.hansson@...aro.org, fabio.estevam@....com,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-imx@....com,
        Peng Fan <peng.fan@....com>
Subject: [RFC] platform: detach from PM domains on shutdown

When reboot Linux, the PM domains attached to a device
are not shutdown. To SoCs which relys on reset the whole SoC,
there is no need to shutdown PM domains, but to Linux running
in a virtual machine with devices pass-through, we could not
reset the whole SoC. Currently we need Linux to shutdown its
PM domains when reboot.

commit 2d30bb0b3889 ("platform: Do not detach from PM domains on shutdown"),
removes what this patch tries to add, because of a warning.
commit e79aee49bcf9 ("PM: Avoid false-positive warnings in dev_pm_domain_set()")
already fixes the false alarm warning. So let's detach the power domain
to shutdown PM domains after driver shutdown.

Signed-off-by: Peng Fan <peng.fan@....com>
---

I do not find a better place to shutdown power domain when reboot Linux,
so add back the line that commit 2d30bb0b3889 removes, because it is
a false alarm warning as commit e79aee49bcf9 describes.

 drivers/base/platform.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 8075ddc70a17..a5929f24dc3c 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -616,6 +616,7 @@ static void platform_drv_shutdown(struct device *_dev)

 	if (drv->shutdown)
 		drv->shutdown(dev);
+	dev_pm_domain_detach(_dev, true);
 }

 /**
-- 
2.14.1