[RFC PATCH 1/2] ARM: imx: add BYPASS support for PLL clocks

[Shawn Guo]

On Fri, Aug 29, 2014 at 11:33:47AM +0800, Shengjiu Wang wrote:
> Otherwise I still need to do some step in below to source the clock to ESAI.
> 
>         clk_set_parent(pll4_bypass_src, lvds2_in);
>         clk_set_parent(pll4_bypass, pll4_bypass_src);
>         clk_set_rate(pll4_audio_div, 24576000);
>         clk_set_rate(esai_extal, 24576000);
> 
> I think it is what we can expect, right? if yes, the patch is ok for ESAI.

Yes, we still need to set up parent and rate specifically for
sabreauto ESAI use case.

But these setup can be done in device tree now with commit 86be408bfbd8
(clk: Support for clock parents and rates assigned from device tree).
Here is change that I tested with.  (Not sure if the info in esai node
is all correct)

diff --git a/arch/arm/boot/dts/imx6qdl.dtsi b/arch/arm/boot/dts/imx6qdl.dtsi
index 6692115b0138..9fe4169c79dd 100644
--- a/arch/arm/boot/dts/imx6qdl.dtsi
+++ b/arch/arm/boot/dts/imx6qdl.dtsi
@@ -268,8 +268,18 @@
                                };

                                esai: esai at 02024000 {
+                                       compatible = "fsl,imx6q-esai", "fsl,imx35-esai";
                                        reg = <0x02024000 0x4000>;
                                        interrupts = <0 51 IRQ_TYPE_LEVEL_HIGH>;
+                                       clocks = <&clks IMX6QDL_CLK_ESAI_IPG>,
+                                                <&clks IMX6QDL_CLK_ESAI_EXTAL>,
+                                                <&clks IMX6QDL_CLK_ESAI_IPG>;
+                                       clock-names = "core", "extal", "fsys";
+                                       dmas = <&sdma 23 21 0>, <&sdma 24 21 0>;
+                                       dma-names = "rx", "tx";
+                                       fsl,fifo-depth = <128>;
+                                       fsl,esai-synchronous;
+                                       status = "disabled";
                                };

                                ssi1: ssi at 02028000 {

diff --git a/arch/arm/boot/dts/imx6qdl-sabreauto.dtsi b/arch/arm/boot/dts/imx6qdl-sabreauto.dtsi
index 009abd69385d..1084394197ad 100644
--- a/arch/arm/boot/dts/imx6qdl-sabreauto.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-sabreauto.dtsi
@@ -17,6 +17,14 @@
                reg = <0x10000000 0x80000000>;
        };

+       clocks {
+               anaclk2 { /* on-board 24.576MHz audio oscillator */
+                       compatible = "fixed-clock";
+                       #clock-cells = <0>;
+                       clock-frequency = <24576000>;
+               };
+       };
+
        leds {
                compatible = "gpio-leds";
                pinctrl-names = "default";
@@ -45,6 +53,17 @@
        };
 };

+&clks {
+       assigned-clocks = <&clks IMX6QDL_PLL4_BYPASS_SRC>,
+                         <&clks IMX6QDL_PLL4_BYPASS>,
+                         <&clks IMX6QDL_CLK_ESAI_SEL>,
+                         <&clks IMX6QDL_CLK_PLL4_POST_DIV>;
+       assigned-clock-parents = <&clks IMX6QDL_CLK_LVDS2_IN>,
+                                <&clks IMX6QDL_PLL4_BYPASS_SRC>,
+                                <&clks IMX6QDL_CLK_PLL4_AUDIO_DIV>;
+       assigned-clock-rates = <0>, <0>, <0>, <24576000>;
+};
+
 &ecspi1 {
        fsl,spi-num-chipselects = <1>;
        cs-gpios = <&gpio3 19 0>;
@@ -61,6 +80,12 @@
        };
 };

+&esai {
+       assigned-clocks = <&clks IMX6QDL_CLK_ESAI_EXTAL>;
+       assigned-clock-rates = <24576000>;
+       status = "okay";
+};
+
 &fec {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_enet>;


With above dts changes, I can get the following clock setup for ESAI.

 anaclk2                                  0            0    24576000          0
    lvds2_in                              0            0    24576000          0
       pll4_bypass_src                    0            0    24576000          0
          pll4_bypass                     0            0    24576000          0
             pll4_audio                   0            0    24576000          0
                pll4_post_div             0            0    24576000          0
                   pll4_audio_div           0            0    24576000          0
                      esai_sel            0            0    24576000          0
                         esai_pred           0            0    24576000          0
                            esai_podf           0            0    24576000          0
                               esai_extal           0            0    24576000          0

Shawn