linux-kernel - [PATCH 1/2] ARM: EXYNOS: Get current parent clock for power domain on/off

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Date:	Thu, 02 Apr 2015 10:06:18 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Kukjin Kim <kgene@...nel.org>, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Subject: [PATCH 1/2] ARM: EXYNOS: Get current parent clock for power domain
 on/off

Using a fixed (by DTS) parent for clocks when turning on the power domain
may introduce issues in other drivers. For example when such driver
changes the parent during runtime and expects that he is the only place
of such change.

Do not rely entirely on DTS providing the fixed parent for such clocks.
Instead if "pclkN" clock name is missing, grab a current parent of clock
with clk_get_parent().

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
---
 Documentation/devicetree/bindings/arm/exynos/power_domain.txt | 8 +++++---
 arch/arm/mach-exynos/pm_domains.c                             | 9 ++++++---
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/arm/exynos/power_domain.txt b/Documentation/devicetree/bindings/arm/exynos/power_domain.txt
index 5da38c5ed476..0fc1312f6fd5 100644
--- a/Documentation/devicetree/bindings/arm/exynos/power_domain.txt
+++ b/Documentation/devicetree/bindings/arm/exynos/power_domain.txt
@@ -19,9 +19,11 @@ Optional Properties:
 	domains.
 - clock-names: The following clocks can be specified:
 	- oscclk: Oscillator clock.
-	- pclkN, clkN: Pairs of parent of input clock and input clock to the
-		devices in this power domain. Maximum of 4 pairs (N = 0 to 3)
-		are supported currently.
+	- pclkN, clkN: Input clocks (clkN) to the devices in this power domain.
+		Optionally with parrents (pclkN). If such parent is provided
+		it will be used for reparenting the given clock when domain
+		is turned on. Otherwise the parent before power down will be
+		used. Maximum of 4 pairs (N = 0 to 3) are supported currently.
 	- asbN: Clocks required by asynchronous bridges (ASB) present in
 		the power domain. These clock should be enabled during power
 		domain on/off operations.
diff --git a/arch/arm/mach-exynos/pm_domains.c b/arch/arm/mach-exynos/pm_domains.c
index cbe56b35aea0..c55bcf52a6ad 100644
--- a/arch/arm/mach-exynos/pm_domains.c
+++ b/arch/arm/mach-exynos/pm_domains.c
@@ -37,6 +37,7 @@ struct exynos_pm_domain {
 	struct clk *oscclk;
 	struct clk *clk[MAX_CLK_PER_DOMAIN];
 	struct clk *pclk[MAX_CLK_PER_DOMAIN];
+	unsigned int pclk_dynamic:MAX_CLK_PER_DOMAIN;
 	struct clk *asb_clk[MAX_CLK_PER_DOMAIN];
 };
 
@@ -62,6 +63,9 @@ static int exynos_pd_power(struct generic_pm_domain *domain, bool power_on)
 		for (i = 0; i < MAX_CLK_PER_DOMAIN; i++) {
 			if (IS_ERR(pd->clk[i]))
 				break;
+			/* If parent was not set in DT, save current parent */
+			if (pd->pclk_dynamic & (1 << i))
+				pd->pclk[i] = clk_get_parent(pd->clk[i]);
 			if (clk_set_parent(pd->clk[i], pd->oscclk))
 				pr_err("%s: error setting oscclk as parent to clock %d\n",
 						pd->name, i);
@@ -164,9 +168,8 @@ static __init int exynos4_pm_init_power_domain(void)
 			snprintf(clk_name, sizeof(clk_name), "pclk%d", i);
 			pd->pclk[i] = clk_get(dev, clk_name);
 			if (IS_ERR(pd->pclk[i])) {
-				clk_put(pd->clk[i]);
-				pd->clk[i] = ERR_PTR(-EINVAL);
-				break;
+				pd->pclk_dynamic |= (1 << i);
+				pd->pclk[i] = clk_get_parent(pd->clk[i]);
 			}
 		}
 
-- 
1.9.1

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