Messages in this thread | | | Date | Wed, 25 Oct 2023 15:47:55 +0200 | From | Stephan Gerhold <> | Subject | Re: [PATCH 1/2] OPP: Use _set_opp_level() for single genpd case |
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On Wed, Oct 25, 2023 at 12:40:26PM +0200, Ulf Hansson wrote: > On Wed, 25 Oct 2023 at 08:55, Viresh Kumar <viresh.kumar@linaro.org> wrote: > > > > On 19-10-23, 13:16, Ulf Hansson wrote: > > > On Thu, 19 Oct 2023 at 12:22, Viresh Kumar <viresh.kumar@linaro.org> wrote: > > > > +static int _link_required_opps(struct dev_pm_opp *opp, struct opp_table *opp_table, > > > > struct opp_table *required_table, int index) > > > > { > > > > struct device_node *np; > > > > @@ -314,6 +314,25 @@ static int _link_required_opps(struct dev_pm_opp *opp, > > > > return -ENODEV; > > > > } > > > > > > > > + /* > > > > + * There are two genpd (as required-opp) cases that we need to handle, > > > > + * devices with a single genpd and ones with multiple genpds. > > > > + * > > > > + * The single genpd case requires special handling as we need to use the > > > > + * same `dev` structure (instead of a virtual one provided by genpd > > > > + * core) for setting the performance state. Lets treat this as a case > > > > + * where the OPP's level is directly available without required genpd > > > > + * link in the DT. > > > > + * > > > > + * Just update the `level` with the right value, which > > > > + * dev_pm_opp_set_opp() will take care of in the normal path itself. > > > > + */ > > > > + if (required_table->is_genpd && opp_table->required_opp_count == 1 && > > > > + !opp_table->genpd_virt_devs) { > > > > + if (!WARN_ON(opp->level)) > > > > > > Hmm. Doesn't this introduce an unnecessary limitation? > > > > > > An opp node that has a required-opps phande, may have "opp-hz", > > > "opp-microvolt", etc. Why would we not allow the "opp-level" to be > > > used too? > > > > Coming back to this, why would we ever want a device to have "opp-level" and > > "required-opp" (set to genpd's table) ? That would mean we will call: > > > > dev_pm_domain_set_performance_state() twice to set different level values. > > Yes - and that would be weird, especially since the PM domain (genpd) > is already managing the aggregation and propagation to parent domains. >
FWIW I'm hitting this WARNing when trying to set up the parent domain setup for CPR->RPMPD(MX) on MSM8916 that I discussed with Uffe recently [1]. I know, me and all my weird OPP setups. :'D
Basically, I have cpufreq voting for performance states of the CPR genpd (via required-opps). CPR is supposed to have <&rpmpd MSM8916_VDDMX_AO> as parent genpd and translates to the parent performance state using the "required-opps" in the *CPR* OPP table:
cpr: power-controller@b018000 { compatible = "qcom,msm8916-cpr", "qcom,cpr"; reg = <0x0b018000 0x1000>; /* ... */ #power-domain-cells = <0>; operating-points-v2 = <&cpr_opp_table>; /* Supposed to be parent domain, not consumer */ power-domains = <&rpmpd MSM8916_VDDMX_AO>;
cpr_opp_table: opp-table { compatible = "operating-points-v2-qcom-level";
cpr_opp1: opp1 { opp-level = <1>; qcom,opp-fuse-level = <1>; required-opps = <&rpmpd_opp_svs_soc>; }; cpr_opp2: opp2 { opp-level = <2>; qcom,opp-fuse-level = <2>; required-opps = <&rpmpd_opp_nom>; }; cpr_opp3: opp3 { opp-level = <3>; qcom,opp-fuse-level = <3>; required-opps = <&rpmpd_opp_super_turbo>; }; }; };
There are two problems with this:
1. (Unrelated to $subject patch) Since there is only a single entry in "power-domains", the genpd core code automatically attaches the CPR platform device as consumer of the VDDMX_AO power domain. I don't want this, I want it to become child of the VDDMX_AO genpd.
I added some hacky code to workaround this. One option that works is to add a second dummy entry to "power-domains", which will prevent the genpd core from attaching the power domain:
power-domains = <&rpmpd MSM8916_VDDMX_AO>, <0>;
The other option is detaching the power domain again in probe(), after setting it up as parent domain:
struct of_phandle_args parent, child;
child.np = dev->of_node; child.args_count = 0;
of_parse_phandle_with_args(dev->of_node, "power-domains", "#power-domain-cells", 0, &parent)); of_genpd_add_subdomain(&parent, &child);
/* Detach power domain since it's managed via the subdomain */ dev_pm_domain_detach(dev, false);
Is there a cleaner way to handle this? Mainly a question for Uffe.
2. The OPP WARNing triggers with both variants because it just checks if "required-opps" has a single entry. I guess we need extra checks to exclude the "parent genpd" case compared to the "OPP" case.
[ 1.116244] WARNING: CPU: 2 PID: 36 at drivers/opp/of.c:331 _link_required_opps+0x180/0x1cc [ 1.125897] Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT) [ 1.146887] pc : _link_required_opps+0x180/0x1cc [ 1.146902] lr : _link_required_opps+0xdc/0x1cc [ 1.276408] Call trace: [ 1.283519] _link_required_opps+0x180/0x1cc [ 1.285779] _of_add_table_indexed+0x61c/0xd40 [ 1.290292] dev_pm_opp_of_add_table+0x10/0x18 [ 1.294546] of_genpd_add_provider_simple+0x80/0x160 [ 1.298974] cpr_probe+0x6a0/0x97c [ 1.304092] platform_probe+0x64/0xbc
It does seem to work correctly, with and without this patch. So I guess another option might be to simply silence this WARN_ON(). :')
Thanks, Stephan
[1]: https://lore.kernel.org/linux-pm/CAPDyKFoH5EOvRRKy-Bgp_B9B3rf=PUKK5N45s5PNgfBi55PaOQ@mail.gmail.com/
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