From 2a9a06f98f26654d3b07482319ea0be276689f0b Mon Sep 17 00:00:00 2001 From: Joachim Eastwood Date: Sat, 24 Oct 2015 18:55:23 +0200 Subject: [PATCH] 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: Joachim Eastwood Signed-off-by: Stephen Boyd --- drivers/clk/nxp/clk-lpc18xx-ccu.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/clk/nxp/clk-lpc18xx-ccu.c b/drivers/clk/nxp/clk-lpc18xx-ccu.c index eeaee97da110..13aabbb3acbe 100644 --- a/drivers/clk/nxp/clk-lpc18xx-ccu.c +++ b/drivers/clk/nxp/clk-lpc18xx-ccu.c @@ -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 = { -- 2.39.5