mx6ul: Finding a good place to configure SAI2_MCLK

[Fabio Estevam]

Hi,

In order to get audio working on imx6ul-evk board we need to enable
the SAI2 MCLK clock by setting bit 20 (SAI2_MCLK_DIR) of the
IOMUXC_GPR_GPR1 register.

I am not sure where is the appropriate place to set this bit.

Doing like this works fine:

--- a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
+++ b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
@@ -447,5 +447,6 @@
 #define IMX6UL_GPR1_ENET2_CLK_OUTPUT           (0x1 << 18)
 #define IMX6UL_GPR1_ENET_CLK_DIR               (0x3 << 17)
 #define IMX6UL_GPR1_ENET_CLK_OUTPUT            (0x3 << 17)
+#define IMX6UL_GPR1_SAI2_MCLK_DIR              (0x1 << 20)

index a38b16b..92cfb0f 100644
--- a/arch/arm/mach-imx/mach-imx6ul.c
+++ b/arch/arm/mach-imx/mach-imx6ul.c
@@ -56,6 +56,19 @@ static inline void imx6ul_enet_init(void)
        imx6ul_enet_phy_init();
 }

+static void __init imx6ul_mclk_init(void)
+{
+       struct regmap *gpr;
+
+       gpr = syscon_regmap_lookup_by_compatible("fsl,imx6ul-iomuxc-gpr");
+       if (!IS_ERR(gpr))
+               regmap_update_bits(gpr, IOMUXC_GPR1, IMX6UL_GPR1_SAI2_MCLK_DIR,
+                                  IMX6UL_GPR1_SAI2_MCLK_DIR);
+       else
+               pr_err("failed to find fsl,imx6ul-iomux-gpr regmap\n");
+
+}
+
 static void __init imx6ul_init_machine(void)
 {
        struct device *parent;
@@ -68,6 +81,7 @@ static void __init imx6ul_init_machine(void)
        imx6ul_enet_init();
        imx_anatop_init();
        imx6ul_pm_init();
+       imx6ul_mclk_init();
 }

but it does not seem correct as this should be board specific. Should
we call it only if the compatible string matches imx6sl-14x14-evk
string? Looks like that will not scale as well.

Currently in arch/arm/mach-imx/mach-imx6ul.c we also have
imx6ul_enet_clk_init() function which sets the ENET_CLK in the GPR1
register.

IMHO this is not correct because not all mx6ul boards need such clock
and then we need to change this too.

So where should we set the SAI2_MCLK_DIR bit of GPR1? Inside the SAI driver?

Appreciate some feedback.

Thanks,

Fabio Estevam