[PATCH 4.9 099/138] clk: sunxi-ng: fix PLL_CPUX adjusting on A33

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Icenowy Zheng <icenowy@xxxxxxxx>


[ Upstream commit 790d929b540661945d1c70652ffb602c5c06ad85 ]

When adjusting PLL_CPUX on A33, the PLL is temporarily driven too high,
and the system hangs.

Add a notifier to avoid this situation by temporarily switching to a
known stable 24 MHz oscillator.

Signed-off-by: Icenowy Zheng <icenowy@xxxxxxxx>
Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/clk/sunxi-ng/ccu-sun8i-a33.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/drivers/clk/sunxi-ng/ccu-sun8i-a33.c
+++ b/drivers/clk/sunxi-ng/ccu-sun8i-a33.c
@@ -752,6 +752,13 @@ static const struct sunxi_ccu_desc sun8i
 	.num_resets	= ARRAY_SIZE(sun8i_a33_ccu_resets),
 };
 
+static struct ccu_mux_nb sun8i_a33_cpu_nb = {
+	.common		= &cpux_clk.common,
+	.cm		= &cpux_clk.mux,
+	.delay_us	= 1, /* > 8 clock cycles at 24 MHz */
+	.bypass_index	= 1, /* index of 24 MHz oscillator */
+};
+
 static void __init sun8i_a33_ccu_setup(struct device_node *node)
 {
 	void __iomem *reg;
@@ -775,6 +782,9 @@ static void __init sun8i_a33_ccu_setup(s
 	writel(val, reg + SUN8I_A33_PLL_MIPI_REG);
 
 	sunxi_ccu_probe(node, reg, &sun8i_a33_ccu_desc);
+
+	ccu_mux_notifier_register(pll_cpux_clk.common.hw.clk,
+				  &sun8i_a33_cpu_nb);
 }
 CLK_OF_DECLARE(sun8i_a33_ccu, "allwinner,sun8i-a33-ccu",
 	       sun8i_a33_ccu_setup);