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Commit 2a9a06f9 authored by Joachim Eastwood's avatar Joachim Eastwood Committed by Stephen Boyd
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clk: lpc18xx-ccu: fix potential system hang when disabling unused clocks 



CCU branch clock register must only be accessed while the base
(parent) clock is running. Access with a disabled base clock
will cause the system to hang. Fix this issue by adding code
that check if the parent clock is running in the is_enabled
clk_ops callback.

This hang would occur when disabling unused clocks after AMBA
runtime pm had already disabled some of the clocks.

Signed-off-by: default avatarJoachim Eastwood <manabian@gmail.com>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
parent be68bf88

drivers/clk/nxp/clk-lpc18xx-ccu.c

+15 −2
Original line number Diff line number Diff line
@@ -179,9 +179,22 @@ static void lpc18xx_ccu_gate_disable(struct clk_hw *hw) 


static int lpc18xx_ccu_gate_is_enabled(struct clk_hw *hw)

{

	struct clk_gate *gate = to_clk_gate(hw);

	const struct clk_hw *parent;



	/*

	 * The branch clock registers are only accessible

	 * if the base (parent) clock is enabled. Register

	 * access with a disabled base clock will hang the

	 * system.

	 */

	parent = clk_hw_get_parent(hw);

	if (!parent)

		return 0;



	if (!clk_hw_is_enabled(parent))

		return 0;



	return clk_readl(gate->reg) & LPC18XX_CCU_RUN;

	return clk_gate_ops.is_enabled(hw);

}



static const struct clk_ops lpc18xx_ccu_gate_ops = {