Re: [PATCH] clk: mvebu: armada-37xx-periph: Fix initialization for cpu clocks

Hello Christian,

Hi,

I assume you use the 1000 MHz firmware. This does also not work on my Rev 7 board. But I'm pretty sure this is not a problem of the patches, because if I take a newer kernel (4.19.20/27) without the patches it also does not work. A kernel 4.19.17 does work for me. My opinion on that is that this is another problem which does just occure now because now the cpu frequency scaling is working with the right frequencies.

I am not sure which firmware i am running, i did all my tests on 5.0.0 and changing between governors worked fine without the patches

Regards /Ilias

Ilias Apalodimas ilias.apalodimas@linaro.org schrieb am Do., 14. März 2019, 13:15:

...

Hi Gregory,

...

The clock parenting was not setup properly when DVFS was enabled. It was expected that the same clock source was used with and without DVFS which was not the case.

This patch fixes this issue, allowing to make the cpufreq support work when the CPU clocks source are not the default ones.

Fixes: 92ce45fb875d ("cpufreq: Add DVFS support for Armada 37xx") Cc: stable@vger.kernel.org Reported-by: Christian Neubert christian.neubert.86@gmail.com Reported-by: Ilias Apalodimas ilias.apalodimas@linaro.org Signed-off-by: Gregory CLEMENT gregory.clement@bootlin.com

---

drivers/clk/mvebu/armada-37xx-periph.c | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/drivers/clk/mvebu/armada-37xx-periph.c

b/drivers/clk/mvebu/armada-37xx-periph.c

...

index 1f1cff428d78..26ed3c18a239 100644 --- a/drivers/clk/mvebu/armada-37xx-periph.c +++ b/drivers/clk/mvebu/armada-37xx-periph.c @@ -671,6 +671,17 @@ static int armada_3700_add_composite_clk(const

struct clk_periph_data *data,

...

          map = syscon_regmap_lookup_by_compatible(
                          "marvell,armada-3700-nb-pm");
          pmcpu_clk->nb_pm_base = map;

•         /*
  

•          * Use the same parent when DVFS is enabled that the
  

•          * default parent received at boot time. When this
  

•          * function is called, DVFS is not enabled yet, so we
  

•          * get the default parent and we can set the parent
  

•          * for DVFS.
  

•          */
  

•         if (clk_pm_cpu_set_parent(muxrate_hw,
  

clk_pm_cpu_get_parent(muxrate_hw)))

...

•                 dev_warn(dev, "Failed to setup default parent
  

clock for DVFS\n");

...

  }

  *hw = clk_hw_register_composite(dev, data->name,

data->parent_names,

...

-- 2.20.1

Applied this and selected only

CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y CONFIG_CPU_FREQ_GOV_PERFORMANCE=y CONFIG_CPU_FREQ_GOV_POWERSAVE=y

After changing the governor from 'powersave' to 'performance' the board completely froze (i even lost access to the serial port)

Cheers /Ilias