[PATCH v2 05/21] ARM: tegra: clock: Disable clocks left on by bootloader

Colin Cross
2011-02-19T22:26:26Z

Adds CONFIG_TEGRA_DISABLE_BOOTLOADER_CLOCKS that iterates
through all clocks, disabling any for which the refcount
is 0 but the clock init detected the bootloader left the
clock on.

Signed-off-by: Colin Cross <ccross@android.com>
---
arch/arm/mach-tegra/Kconfig | 6 ++++++
arch/arm/mach-tegra/clock.c | 30 ++++++++++++++++++++++++++++++
2 files changed, 36 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index f0fda77..9f4fc6b 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -57,6 +57,12 @@ config TEGRA_DEBUG_UARTE

endchoice

+config TEGRA_DISABLE_BOOTLOADER_CLOCKS
+ bool "Disable clocks left on by bootloader"
+ help
+ Disables clocks that are detected to be on but haven't
+ been requested by a kernel driver.
+
config TEGRA_SYSTEM_DMA
bool "Enable system DMA driver for NVIDIA Tegra SoCs"
default y
diff --git a/arch/arm/mach-tegra/clock.c b/arch/arm/mach-tegra/clock.c
index f55bb83..0ea5d92 100644
--- a/arch/arm/mach-tegra/clock.c
+++ b/arch/arm/mach-tegra/clock.c
@@ -511,6 +511,36 @@ int __init tegra_init_dvfs(void)

late_initcall(tegra_init_dvfs);

+/*
+ * Iterate through all clocks, disabling any for which the refcount is 0
+ * but the clock init detected the bootloader left the clock on.
+ */
+#ifdef CONFIG_TEGRA_DISABLE_BOOTLOADER_CLOCKS
+int __init tegra_disable_boot_clocks(void)
+{
+ unsigned long flags;
+
+ struct clk *c;
+
+ spin_lock_irqsave(&clock_lock, flags);
+
+ list_for_each_entry(c, &clocks, node) {
+ if (c->refcnt == 0 && c->state == ON &&
+ c->ops && c->ops->disable) {
+ pr_warning("Disabling clock %s left on by bootloader\n",
+ c->name);
+ c->ops->disable(c);
+ c->state = OFF;
+ }
+ }
+
+ spin_unlock_irqrestore(&clock_lock, flags);
+
+ return 0;
+}
+late_initcall(tegra_disable_boot_clocks);
+#endif
+
#ifdef CONFIG_DEBUG_FS
static struct dentry *clk_debugfs_root;

--
1.7.3.1