Christian Hewitt <christianshewitt@xxxxxxxxx> writes:
>> On 10 Feb 2022, at 5:31 am, Kevin Hilman <khilman@xxxxxxxxxxxx> wrote:
>>
>> Christian Hewitt <christianshewitt@xxxxxxxxx> writes:
>>
>>> Amlogic G12B and SM1 devices experience CPU stalls and random board
>>> wedges when the system idles and CPU cores clock down to lower opp
>>> points. Recent vendor kernels include a change to remove 100-250MHz
>>> (with no explanation) [0] but other downstream sources also remove
>>> the 500/667MHz points (also with no explanation). Unless 100-667Mhz
>>> opps are removed or the CPU governor forced to performance, stalls
>>> are observed, so let's remove them an improve stability/uptime.
>>
>> Just curious: what CPUfreq governor do you use by default for the
>> LibreELEC kernel?
>
> LE uses ondemand. One of the original clues on the problem us that the
> issue isn’t seen in some of the retro-gaming forks on LE's codebase
> which use the performance governor (and overclocks, etc.)
OK, thanks. And does LE ever do full system suspend/resume? Are things
stable for you across multiple suspend/resume cycles on G12B or SM1
devices?
I'm seeing hat with either powersave or performance, repeated
suspend/resume is stable, but with ondemand or schedultil it's not, even
with $SUBJECT patch applied.
If you have some time to test, seeing how long this loop[1] runs with
ondemand vs performance or powersave would be instructive.
Even more interesting... if I set the governor to performance, but set
the suspend OPP to 1GHz[2] (which is what it would be for the powersave
governor), it is also unstable. This suggests (to me) that any sort of
OPP change during the suspend/resume process is going to be unstable.
Now the challenge is to understand why so we can avoid it.
Thanks,
Kevin
[1]
while true; do
echo "=== SUSPEND ==="
cat /sys/devices/system/cpu/cpufreq/policy0/scaling_governor
cat /sys/devices/system/cpu/cpufreq/policy0/scaling_cur_freq
cat /sys/devices/system/cpu/cpufreq/policy2/scaling_governor
cat /sys/devices/system/cpu/cpufreq/policy2/scaling_cur_freq
echo rtcwake -d rtc0 -m mem -s4
echo "=== RESUME ==="
sleep 4
done
[2]
diff --git a/arch/arm64/boot/dts/amlogic/meson-g12b-s922x.dtsi b/arch/arm64/boot/dts/amlogic/meson-g12b-s922x.dtsi
index 1e5d0ee5d541..37da8be85288 100644
--- a/arch/arm64/boot/dts/amlogic/meson-g12b-s922x.dtsi
+++ b/arch/arm64/boot/dts/amlogic/meson-g12b-s922x.dtsi
@@ -14,6 +14,7 @@ cpu_opp_table_0: opp-table-0 {
opp-100000000 {
opp-hz = /bits/ 64 <100000000>;
opp-microvolt = <731000>;
+ opp-suspend;
};
opp-250000000 {
@@ -79,6 +80,7 @@ cpub_opp_table_1: opp-table-1 {
opp-100000000 {
opp-hz = /bits/ 64 <100000000>;
opp-microvolt = <751000>;
+ opp-suspend;
};
opp-250000000 {
