[PATCH 0/6] Add CPU Frequency scaling support on Armada 37xx

[gregory.clement@free-electrons.com (Gregory CLEMENT)]

Hi Andre,
 
 On dim., d?c. 03 2017, Andre Heider <a.heider@gmail.com> wrote:

> Hi Gregory,
>
> I applied this and the dvfs patch set ([PATCH 0/3] Add DVFS support on
> CPU clock for Armada 37xx) on top of 4.14.3 and gave it a try on
> espressobin.

Thanks for testing.

>
> Upon modprobe I get:
> [   66.231652] freq_table: Duplicate freq-table entries: 0
> [   66.236967] cpu cpu0: cpufreq_init: invalid frequency table: -22
> [   66.243534] freq_table: Duplicate freq-table entries: 0
> [   66.248575] cpu cpu1: cpufreq_init: invalid frequency table: -22
>
> Is this supposed to work already? Do I miss something?

I did a last rebase before sending the series to remove the avs part not
working yet. And during this rebase I introduced an bug.

I will send a v2 soon if  you are intersected by testing it right now,
here it is the fix:

iff --git a/drivers/cpufreq/armada-37xx-cpufreq.c b/drivers/cpufreq/armada-37xx-cpufreq.c
index 40c9a744cc6e..96c2600009b5 100644
--- a/drivers/cpufreq/armada-37xx-cpufreq.c
+++ b/drivers/cpufreq/armada-37xx-cpufreq.c
@@ -219,7 +219,8 @@ static int __init armada37xx_cpufreq_driver_init(void)
         */
        for (load_level = ARMADA_37XX_DVFS_LOAD_0; load_level < LOAD_LEVEL_NR;
             load_level++) {
-               unsigned long freq = dvfs->divider[load_level];
+               unsigned long freq = cur_frequency /
+                       dvfs->divider[load_level];
 
                ret = dev_pm_opp_add(cpu_dev, freq, 0);
                if (ret)


Gregory

>
> Oh, and on that scenario it's not possible to rmmod the driver again, EBUSY.
>
> Thanks,
> Andre
>
> On 01/12/17 12:25, Gregory CLEMENT
> <gregory.clement@free-electrons.com> wrote:
>> Hi,
>>
>> This series adds the CPU Frequency support on Armada 37xx using
>> DVFS. It is based on the initial work of Evan Wang and Victor Gu.
>>
>> DVFS control is done by a set of registers from the North Bridge Power
>> Management block. The binding for this block is documented in patch 1.
>>
>> While adding a new cpufreq driver I found that the Kconfig and
>> Makefile were no more in order, so it is fixed by patch 2 and 3.
>>
>> The 4th patch is just about updating the MAINTAINERS file with the new
>> driver.
>>
>> The next patch is the real purpose of the series. The main goal of
>> this driver is to setup the CPU load level in the hardware to
>> associate them to CPU frequencies and register a standard cpufreq
>> driver. Note that the hardware also capable of doing AVS (Adaptive
>> Voltage Scaling), by associating a voltage on each level beside the
>> CPU frequency. However, this support is not yet ready, so it is not
>> part of this series.
>>
>> Finally, the last patch is for arm-soc the arm-soc subsystem through
>> mvebu and update the device tree to support the CPU frequency scaling.
>>
>> An update on the CPU clock driver is needed in order to take into
>> account the DVFS setting. It's the purpose of an other series already
>> sent, but is no dependencies between the series (for building or at
>> runtime).
>>
>> Thanks,
>>
>> Gregory
>>
>> Gregory CLEMENT (6):
>>    dt-bindings: marvell: Add documentation for the North Bridge PM on
>>      Armada 37xx
>>    cpufreq: ARM: sort the Kconfig menu
>>    cpufreq: sort the drivers in ARM part
>>    MAINTAINERS: add new entries for Armada 37xx cpufreq driver
>>    cpufreq: Add DVFS support for Armada 37xx
>>    arm64: dts: marvell: armada-37xx: add nodes allowing cpufreq support
>>
>>   .../bindings/arm/marvell/armada-37xx.txt           |  19 ++
>>   MAINTAINERS                                        |   1 +
>>   arch/arm64/boot/dts/marvell/armada-372x.dtsi       |   1 +
>>   arch/arm64/boot/dts/marvell/armada-37xx.dtsi       |   7 +
>>   drivers/cpufreq/Kconfig.arm                        |  89 ++++----
>>   drivers/cpufreq/Makefile                           |   9 +-
>>   drivers/cpufreq/armada-37xx-cpufreq.c              | 241 +++++++++++++++++++++
>>   7 files changed, 322 insertions(+), 45 deletions(-)
>>   create mode 100644 drivers/cpufreq/armada-37xx-cpufreq.c
>>
>

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com