Hi Clément,
On Tue, Apr 28, 2020 at 04:26:29PM +0200, Clément Péron wrote:
> Tanix TX6 has a fixed regulator. As DVFS is instructed to change
> voltage to meet OPP table, the DVFS is not working as expected.
>
> Avoid to introduce a new dedicated OPP Table where voltage are
> equals to the fixed regulator as it will only duplicate all the OPPs.
> Instead remove the fixed regulator so the DVFS framework will create
> dummy regulator and will have the same behavior.
>
> Add some comments to explain this in the device-tree.
>
> Reported-by: Piotr Oniszczuk <war...@o2.pl>
> Fixes: add1e27fb703 ("arm64: dts: allwinner: h6: Enable CPU opp tables for
> Tanix TX6")
> Signed-off-by: Clément Péron <peron.c...@gmail.com>
> ---
> .../boot/dts/allwinner/sun50i-h6-tanix-tx6.dts | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6-tanix-tx6.dts
> b/arch/arm64/boot/dts/allwinner/sun50i-h6-tanix-tx6.dts
> index be81330db14f..3e96fcb317ea 100644
> --- a/arch/arm64/boot/dts/allwinner/sun50i-h6-tanix-tx6.dts
> +++ b/arch/arm64/boot/dts/allwinner/sun50i-h6-tanix-tx6.dts
> @@ -48,7 +48,15 @@
> };
>
> &cpu0 {
> - cpu-supply = <®_vdd_cpu_gpu>;
> + /*
> + * Don't specify the CPU regulator, as it's a fixed
> + * regulator DVFS will not work as it is intructed
> + * to reach a voltage which can't be reached.
> + * Not specifying a regulator will create a dummy
> + * regulator allowing all OPPs.
> + *
> + * cpu-supply = <®_vdd_cpu_gpu>;
> + */
reg_vdd_cpu_gpu has
regulator-min-microvolt = <1135000>;
regulator-max-microvolt = <1135000>;
top OPP is:
opp@1800000000 {
clock-latency-ns = <244144>; /* 8 32k periods */
opp-hz = /bits/ 64 <1800000000>;
opp-microvolt-speed0 = <1160000>;
opp-microvolt-speed1 = <1100000>;
opp-microvolt-speed2 = <1100000>;
};
So I guess ignoring the voltage and not disabling this OPP may or may not work
based on SoC bin.
On Orange Pi One, there's a regulator that supports two voltages (that can't
support all the listed OPPs for H3), and cpufreq-dt can deal with that
automagically, if you specify OPP voltages via a tripplet of [prefered min max].
Kernell will log this in dmesg on boot:
[ 0.672440] core: _opp_supported_by_regulators: OPP minuV: 1320000 maxuV:
1320000, not supported by regulator
[ 0.672454] cpu cpu0: _opp_add: OPP not supported by regulators (1104000000)
[ 0.672523] core: _opp_supported_by_regulators: OPP minuV: 1320000 maxuV:
1320000, not supported by regulator
[ 0.672530] cpu cpu0: _opp_add: OPP not supported by regulators (1200000000)
[ 0.672621] core: _opp_supported_by_regulators: OPP minuV: 1340000 maxuV:
1340000, not supported by regulator
[ 0.672628] cpu cpu0: _opp_add: OPP not supported by regulators (1296000000)
[ 0.672712] core: _opp_supported_by_regulators: OPP minuV: 1400000 maxuV:
1400000, not supported by regulator
[ 0.672719] cpu cpu0: _opp_add: OPP not supported by regulators (1368000000)
And the list of available OPPs will be reduced at runtime to a supportable
set by the CPU regulator.
If you look at:
https://megous.com/git/linux/commit/?h=ths-5.7&id=d231770195913cf543c0cf9539deee2ecec06680
you'll see a bunch of OPPs for H3 that are specified as a range. So
for example if you want 480MHz, and your regulator can't produce
1.04V exactly, cpufreq will set the voltage to something supportable
in the range.
I think the proper fix is to fix the OPP table for H6, so that it uses
voltage ranges for each OPP and not a single fixed voltage, to support
boards that don't have the standard PMIC that goes with H6.
regards,
o.
> };
>
> &de {
> @@ -68,7 +76,13 @@
> };
>
> &gpu {
> - mali-supply = <®_vdd_cpu_gpu>;
> + /*
> + * Don't specify the GPU regulator, see comment
> + * above for the CPU supply.
> + *
> + * mali-supply = <®_vdd_cpu_gpu>;
> + */
> +
> status = "okay";
> };
>
> --
> 2.20.1
>
> --
> You received this message because you are subscribed to the Google Groups
> "linux-sunxi" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to linux-sunxi+unsubscr...@googlegroups.com.
> To view this discussion on the web, visit
> https://groups.google.com/d/msgid/linux-sunxi/20200428142629.8950-1-peron.clem%40gmail.com.
--
You received this message because you are subscribed to the Google Groups
"linux-sunxi" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to linux-sunxi+unsubscr...@googlegroups.com.
To view this discussion on the web, visit
https://groups.google.com/d/msgid/linux-sunxi/20200504122742.er2jd67bvrn2rfgp%40core.my.home.
