The only way for a fixed factor clock to change its rate would be to change
its parent rate.

Since passing blindly CLK_SET_RATE_PARENT might break a lot of platforms
that were relying on the fact that the parent rate wouldn't change,
introduce a compatible-based whitelist that will allow clocks to opt-in
that flag.

Signed-off-by: Maxime Ripard <redacted>
---
 .../devicetree/bindings/clock/fixed-factor-clock.txt          |  4 ++++
 drivers/clk/clk-fixed-factor.c                                | 11 ++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/clock/fixed-factor-clock.txt b/Documentation/devicetree/bindings/clock/fixed-factor-clock.txt
index 1bae8527eb9b..189467a7188a 100644
--- a/Documentation/devicetree/bindings/clock/fixed-factor-clock.txt
+++ b/Documentation/devicetree/bindings/clock/fixed-factor-clock.txt

@@ -14,6 +14,10 @@ Required properties:
 Optional properties:
 - clock-output-names : From common clock binding.
 
+Some clocks that require special treatments are also handled by that
+driver, with the compatibles:
+  - allwinner,sun4i-a10-pll3-2x-clk
+
 Example:
 	clock {
 		compatible = "fixed-factor-clock";

diff --git a/drivers/clk/clk-fixed-factor.c b/drivers/clk/clk-fixed-factor.c
index 75cd6c792cb8..4db3be214077 100644
--- a/drivers/clk/clk-fixed-factor.c
+++ b/drivers/clk/clk-fixed-factor.c

@@ -142,6 +142,11 @@ void clk_hw_unregister_fixed_factor(struct clk_hw *hw)
 EXPORT_SYMBOL_GPL(clk_hw_unregister_fixed_factor);
 
 #ifdef CONFIG_OF
+static const struct of_device_id set_rate_parent_matches[] = {
+	{ .compatible = "allwinner,sun4i-a10-pll3-2x-clk" },
+	{ /* Sentinel */ },
+};
+
 /**
  * of_fixed_factor_clk_setup() - Setup function for simple fixed factor clock
  */

@@ -150,6 +155,7 @@ void __init of_fixed_factor_clk_setup(struct device_node *node)
 	struct clk *clk;
 	const char *clk_name = node->name;
 	const char *parent_name;
+	unsigned long flags = 0;
 	u32 div, mult;
 
 	if (of_property_read_u32(node, "clock-div", &div)) {

@@ -167,7 +173,10 @@ void __init of_fixed_factor_clk_setup(struct device_node *node)
 	of_property_read_string(node, "clock-output-names", &clk_name);
 	parent_name = of_clk_get_parent_name(node, 0);
 
-	clk = clk_register_fixed_factor(NULL, clk_name, parent_name, 0,
+	if (of_match_node(set_rate_parent_matches, node))
+		flags |= CLK_SET_RATE_PARENT;
+
+	clk = clk_register_fixed_factor(NULL, clk_name, parent_name, flags,
 					mult, div);
 	if (!IS_ERR(clk))
 		of_clk_add_provider(node, of_clk_src_simple_get, clk);