clk: meson: meson8b: Make the CCF use the glitch-free VPU mux

The "vpu_0" or "vpu_1" clock trees should not be updated while the
clock is running. Enforce this by setting CLK_SET_RATE_GATE on the
"vpu_0" and "vpu_1" gates. This makes the CCF switch to the "vpu_1"
tree when "vpu_0" is currently active and vice versa, which is exactly
what the vendor driver does when updating the frequency of the VPU
clock.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20200417184127.1319871-5-martin.blumenstingl@googlemail.com

drivers/clk/meson/meson8b.c

@@ -2063,7 +2063,7 @@ static struct clk_regmap meson8b_vpu_0 = {
 			&meson8b_vpu_0_div.hw
 		},
 		.num_parents = 1,
-		.flags = CLK_SET_RATE_PARENT,
+		.flags = CLK_SET_RATE_GATE | CLK_SET_RATE_PARENT,
 	},
 };
 
@@ -2134,10 +2134,18 @@ static struct clk_regmap meson8b_vpu_1 = {
 			&meson8b_vpu_1_div.hw
 		},
 		.num_parents = 1,
-		.flags = CLK_SET_RATE_PARENT,
+		.flags = CLK_SET_RATE_GATE | CLK_SET_RATE_PARENT,
 	},
 };
 
+/*
+ * The VPU clock has two two identical clock trees (vpu_0 and vpu_1)
+ * muxed by a glitch-free switch on Meson8b and Meson8m2. The CCF can
+ * actually manage this glitch-free mux because it does top-to-bottom
+ * updates the each clock tree and switches to the "inactive" one when
+ * CLK_SET_RATE_GATE is set.
+ * Meson8 only has vpu_0 and no glitch-free mux.
+ */
 static struct clk_regmap meson8b_vpu = {
 	.data = &(struct clk_regmap_mux_data){
 		.offset = HHI_VPU_CLK_CNTL,
@@ -2152,7 +2160,7 @@ static struct clk_regmap meson8b_vpu = {
 			&meson8b_vpu_1.hw,
 		},
 		.num_parents = 2,
-		.flags = CLK_SET_RATE_NO_REPARENT,
+		.flags = CLK_SET_RATE_PARENT,
 	},
 };