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Kernel 3.18 for overo - no 720MHz support?

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Kernel 3.18 for overo - no 720MHz support?

Akram Hameed
Hi guys,

Just tinkering with newer kernels and I note that kernel 3.18 complains about my requested mpurate argument of 720:

[    3.723968] cpufreq: __cpufreq_add_dev: CPU0: Running at unlisted freq: 720000 KHz
[    3.734191] cpufreq: __cpufreq_add_dev: CPU0: Unlisted initial frequency changed to: 600000 KHz

Anyone else experienced this? 

Bootloader reports correct max CPU MHz: 

U-Boot 2015.07 (Oct 15 2015 - 12:16:02 +1100)
 
OMAP3530-GP ES3.1.2, CPU-OPP2, L3-165MHz, Max CPU Clock 720 MHz

Cpufreq-info reckons the hardware will only scale to a lower OPP though:

root@overo:~# cpufreq-info 
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to [hidden email], please.
analyzing CPU 0:
  driver: cpufreq-dt
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 300 us.
  hardware limits: 125 MHz - 600 MHz
  available frequency steps: 125 MHz, 250 MHz, 500 MHz, 550 MHz, 600 MHz
  available cpufreq governors: userspace, performance
  current policy: frequency should be within 125 MHz and 600 MHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 600 MHz (asserted by call to hardware).
  cpufreq stats: 125 MHz:0.00%, 250 MHz:0.00%, 500 MHz:0.00%, 550 MHz:0.00%, 600 MHz:100.00%

Thoughts? Anyone else have this behaviour? I should note for the record I have reconfigured from the default kernel, I can attach the defconfig if you like.


Our company is considering moving to DM3730 overos anyway, but we have a fair few field units running the omap and it's nice to get a little more bang for buck if possible...

Cheers,

Akram

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Re: Kernel 3.18 for overo - no 720MHz support?

Akram Hameed
Hi folks,

Thread necromancy alert - just publishing my solution to this problem in case others need it:

I revisited my issue of wanting OPP6 (720MHz) out of my OMAP3530 part (Overo Water) today. After stuffing about patching the kernel, I realised the solution is actually really simple: just add a line to your device tree files. By way of example, I just hacked omap34xx.dts, patch showing the change with some bonus context is below:

diff --git a/arch/arm/boot/dts/omap34xx.dtsi b/arch/arm/boot/dts/omap34xx.dtsi
index 3819c1e..7d70576 100644
--- a/arch/arm/boot/dts/omap34xx.dtsi
+++ b/arch/arm/boot/dts/omap34xx.dtsi
@@ -14,20 +14,21 @@
        cpus {
                cpu@0 {
                        /* OMAP343x/OMAP35xx variants OPP1-5 */
                        operating-points = <
                                /* kHz    uV */
                                125000   975000
                                250000  1075000
                                500000  1200000
                                550000  1270000
                                600000  1350000
+                               720000  1350000
                        >;
                        clock-latency = <300000>; /* From legacy driver */
                };
        };
 
        ocp {
                omap3_pmx_core2: pinmux@480025d8 {


I can then use 720MHz OPP by either specifying the mpurate kernel argument or changing to the userspace cpu-freq governor and doing a cpufreq-set.

Cheers,

Akram

On Fri, Oct 16, 2015 at 10:12 AM, Akram Hameed <[hidden email]> wrote:
Hi guys,

Just tinkering with newer kernels and I note that kernel 3.18 complains about my requested mpurate argument of 720:

[    3.723968] cpufreq: __cpufreq_add_dev: CPU0: Running at unlisted freq: 720000 KHz
[    3.734191] cpufreq: __cpufreq_add_dev: CPU0: Unlisted initial frequency changed to: 600000 KHz

Anyone else experienced this? 

Bootloader reports correct max CPU MHz: 

U-Boot 2015.07 (Oct 15 2015 - 12:16:02 +1100)
 
OMAP3530-GP ES3.1.2, CPU-OPP2, L3-165MHz, Max CPU Clock 720 MHz

Cpufreq-info reckons the hardware will only scale to a lower OPP though:

root@overo:~# cpufreq-info 
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to [hidden email], please.
analyzing CPU 0:
  driver: cpufreq-dt
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 300 us.
  hardware limits: 125 MHz - 600 MHz
  available frequency steps: 125 MHz, 250 MHz, 500 MHz, 550 MHz, 600 MHz
  available cpufreq governors: userspace, performance
  current policy: frequency should be within 125 MHz and 600 MHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 600 MHz (asserted by call to hardware).
  cpufreq stats: 125 MHz:0.00%, 250 MHz:0.00%, 500 MHz:0.00%, 550 MHz:0.00%, 600 MHz:100.00%

Thoughts? Anyone else have this behaviour? I should note for the record I have reconfigured from the default kernel, I can attach the defconfig if you like.


Our company is considering moving to DM3730 overos anyway, but we have a fair few field units running the omap and it's nice to get a little more bang for buck if possible...

Cheers,

Akram


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