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imx6 ipg per clocks

Question asked by Roberto Mainetti on Oct 17, 2017
Latest reply on Oct 24, 2017 by gusarambula

Hello,

 

I'm updating the device tree of my custom board, using iMX6QDL, from Linux 3.14 to Linux 4.1, and I found this change, that appears to be made by Anson Huang:

diff --git a/arch/arm/boot/dts/imx6qdl.dtsi b/arch/arm/boot/dts/imx6qdl.dtsi
index 70d7207..8de2801 100644 --- a/arch/arm/boot/dts/imx6qdl.dtsi
+++ b/arch/arm/boot/dts/imx6qdl.dtsi @@ -401,8 +401,9 @@
                      reg = <0x02098000 0x4000>;
                      interrupts = <0 55 IRQ_TYPE_LEVEL_HIGH>;
                      clocks = <&clks IMX6QDL_CLK_GPT_IPG>,
-                          <&clks IMX6QDL_CLK_GPT_IPG_PER>;
-                    clok-names = "ipg", "per";
+                          <&clks IMX6QDL_CLK_GPT_IPG_PER>,
+                          <&clks IMX6QDL_CLK_GPT_3M>;
+                    clock-names = "ipg", "per", "osc_per";


If I apply this patch to my board the debug output changes this way:
BEFORE PATCH:
mxc_clocksource_init 66000000
Switching to timer-based delay loop, resolution 15ns
sched_clock: 32 bits at 66MHz [...]
AFTER PATCH:
mxc_clocksource_init 3000000
Switching to timer-based delay loop, resolution 333ns
sched_clock: 32 bits at 3000kHz [...]

My questions are:

- Should I keep this change?

- Will Linux (or my applications) run slower with this change?

- What are these clocks (ipg, per, osc_per) used for?

 

Sorry if my questions are trivial...

 

Kind Regards,

 

Roberto

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