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authorShawn Guo <shawn.guo@freescale.com>2014-07-07 10:53:51 +0800
committerOlof Johansson <olof@lixom.net>2014-07-07 21:21:11 -0700
commit63288b721a80fb58c00cd47e61a90bc8b33ba588 (patch)
tree486cfe73d009a0b196dd8a6d3b61fb8b3d6194b9
parent069c70cb07105521a095655e707ce9c20bcc6154 (diff)
ARM: imx: fix shared gate clock
Let's say clock A and B are two gate clocks that share the same register bit in hardware. Therefore they are registered as shared gate clocks with imx_clk_gate2_shared(). In a scenario that only clock A is enabled by clk_enable(A) while B is not used, the shared gate will be unexpectedly disabled in hardware. It happens because clk_enable(A) increments the share_count from 0 to 1, while clock B is unused to clock core, and therefore the core function will just disable B by calling clk->ops->disable() directly. The consequence of that call is share_count is decremented to 0 and the gate is disabled in hardware, even though clock A is still in use. The patch fixes the issue by initializing the share_count per hardware state and returns enable state per share_count from .is_enabled() hook, in case it's a shared gate. While at it, add a check in clk_gate2_disable() to ensure it's never called with a zero share_count. Reported-by: Fabio Estevam <fabio.estevam@freescale.com> Fixes: f9f28cdf2167 ("ARM: imx: add shared gate clock support") Signed-off-by: Shawn Guo <shawn.guo@freescale.com> Tested-by: Fabio Estevam <fabio.estevam@freescale.com> Signed-off-by: Olof Johansson <olof@lixom.net>
-rw-r--r--arch/arm/mach-imx/clk-gate2.c31
1 files changed, 23 insertions, 8 deletions
diff --git a/arch/arm/mach-imx/clk-gate2.c b/arch/arm/mach-imx/clk-gate2.c
index 4ba587da89d2..84acdfd1d715 100644
--- a/arch/arm/mach-imx/clk-gate2.c
+++ b/arch/arm/mach-imx/clk-gate2.c
@@ -67,8 +67,12 @@ static void clk_gate2_disable(struct clk_hw *hw)
spin_lock_irqsave(gate->lock, flags);
- if (gate->share_count && --(*gate->share_count) > 0)
- goto out;
+ if (gate->share_count) {
+ if (WARN_ON(*gate->share_count == 0))
+ goto out;
+ else if (--(*gate->share_count) > 0)
+ goto out;
+ }
reg = readl(gate->reg);
reg &= ~(3 << gate->bit_idx);
@@ -78,19 +82,26 @@ out:
spin_unlock_irqrestore(gate->lock, flags);
}
-static int clk_gate2_is_enabled(struct clk_hw *hw)
+static int clk_gate2_reg_is_enabled(void __iomem *reg, u8 bit_idx)
{
- u32 reg;
- struct clk_gate2 *gate = to_clk_gate2(hw);
+ u32 val = readl(reg);
- reg = readl(gate->reg);
-
- if (((reg >> gate->bit_idx) & 1) == 1)
+ if (((val >> bit_idx) & 1) == 1)
return 1;
return 0;
}
+static int clk_gate2_is_enabled(struct clk_hw *hw)
+{
+ struct clk_gate2 *gate = to_clk_gate2(hw);
+
+ if (gate->share_count)
+ return !!(*gate->share_count);
+ else
+ return clk_gate2_reg_is_enabled(gate->reg, gate->bit_idx);
+}
+
static struct clk_ops clk_gate2_ops = {
.enable = clk_gate2_enable,
.disable = clk_gate2_disable,
@@ -116,6 +127,10 @@ struct clk *clk_register_gate2(struct device *dev, const char *name,
gate->bit_idx = bit_idx;
gate->flags = clk_gate2_flags;
gate->lock = lock;
+
+ /* Initialize share_count per hardware state */
+ if (share_count)
+ *share_count = clk_gate2_reg_is_enabled(reg, bit_idx) ? 1 : 0;
gate->share_count = share_count;
init.name = name;

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