linux-kernel - [PATCH] PM / Domains: Don't return -EEXIST at attach when PM domain exists

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Date:   Mon, 14 May 2018 16:52:37 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     "Rafael J . Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        "linux-samsung-soc @ vger . kernel . org" 
        <linux-samsung-soc@...r.kernel.org>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: [PATCH] PM / Domains: Don't return -EEXIST at attach when PM domain exists

As dev_pm_domain_attach() isn't the only way to assign PM domain pointers
to devices, clearly we must allow a device to have the pointer already
being assigned. For this reason, return 0 instead of -EEXIST.

Cc: Sylwester Nawrocki <s.nawrocki@...sung.com>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>
Reported-by: Krzysztof Kozlowski <krzk@...nel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Tested-by: Tested-by: Krzysztof Kozlowski <krzk@...nel.org>
---

Krzysztof reported problems for an Exynos5 board, where some devices are added
to their PM domains (genpd) via calling of_genpd_add_device(). As also pointed
out by Sylvester, this leads to probe failure when dev_pm_domain_attach()
returns -EXISTS.

Rafael, potentially this change could be squashed with the recently queued
patch: "PM / Domains: Check for existing PM domain in dev_pm_domain_attach()",
but perhaps its too late for that and the fix is better applied on top!?

---
 drivers/base/power/common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
index 5e4b481..390868c 100644
--- a/drivers/base/power/common.c
+++ b/drivers/base/power/common.c
@@ -106,7 +106,7 @@ int dev_pm_domain_attach(struct device *dev, bool power_on)
 	int ret;

 	if (dev->pm_domain)
-		return -EEXIST;
+		return 0;

 	ret = acpi_dev_pm_attach(dev, power_on);
 	if (!ret)
-- 
2.7.4