clk: sunxi-ng: h6: Preset hdmi-cec clock parent

H6 manual and BSP clock driver both states that hdmi-cec clock has two
possible parents, osc32k and pll-periph0-2x with 36621 predivider.
Because pll-periph0-2x is always 1.2 GHz, both parents give same
hdmi-cec rate - 32768 Hz, which is exactly the rate needed for HDMI CEC
controller to operate correctly.

However, for some reason, HDMI CEC controller doesn't work if default
parent (osc32k) is used. BSP HDMI driver also always use pll-periph0-2x
as hdmi-cec clock parent.

In order to solve the issue, preset hdmi-cec clock parent to
pll-periph0-2x.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

drivers/clk/sunxi-ng/ccu-sun50i-h6.c

@@ -656,6 +656,8 @@ static const char * const hdmi_cec_parents[] = { "osc32k", "pll-periph0-2x" };
 static const struct ccu_mux_fixed_prediv hdmi_cec_predivs[] = {
 	{ .index = 1, .div = 36621 },
 };
+
+#define SUN50I_H6_HDMI_CEC_CLK_REG		0xb10
 static struct ccu_mux hdmi_cec_clk = {
 	.enable		= BIT(31),
 
@@ -1200,6 +1202,15 @@ static int sun50i_h6_ccu_probe(struct platform_device *pdev)
 	val &= ~(GENMASK(21, 16) | BIT(0));
 	writel(val | (7 << 16), reg + SUN50I_H6_PLL_AUDIO_REG);
 
+	/*
+	 * First clock parent (osc32K) is unusable for CEC. But since there
+	 * is no good way to force parent switch (both run with same frequency),
+	 * just set second clock parent here.
+	 */
+	val = readl(reg + SUN50I_H6_HDMI_CEC_CLK_REG);
+	val |= BIT(24);
+	writel(val, reg + SUN50I_H6_HDMI_CEC_CLK_REG);
+
 	return sunxi_ccu_probe(pdev->dev.of_node, reg, &sun50i_h6_ccu_desc);
 }