Re: [Patch v4 5/7] soc: qcom: Extend RPMh power controller driver to register warming devices.

[Thara Gopinath]

On 2/4/20 12:40 PM, Ulf Hansson wrote:
> On Wed, 20 Nov 2019 at 13:56, Thara Gopinath <thara.gopinath@xxxxxxxxxx> wrote:
> > RPMh power control hosts power domains that can be used as
> > thermal warming devices. Register these power domains
> > with the generic power domain warming device thermal framework.
> >
> > Signed-off-by: Thara Gopinath <thara.gopinath@xxxxxxxxxx>
> > ---
> > v3->v4:
> >          - Introduce a boolean value is_warming_dev in rpmhpd structure to
> >            indicate if a generic power domain can be used as a warming
> >            device or not.With this change, device tree no longer has to
> >            specify which power domain inside the rpmh power domain provider
> >            is a warming device.
> >          - Move registering of warming devices into a late initcall to
> >            ensure that warming devices are registerd after thermal
> >            framework is initialized.
> >
> >   drivers/soc/qcom/rpmhpd.c | 38 +++++++++++++++++++++++++++++++++++++-
> >   1 file changed, 37 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/soc/qcom/rpmhpd.c b/drivers/soc/qcom/rpmhpd.c
> > index 9d37534..5666d1f 100644
> > --- a/drivers/soc/qcom/rpmhpd.c
> > +++ b/drivers/soc/qcom/rpmhpd.c
> > @@ -11,6 +11,7 @@
> >   #include <linux/of_device.h>
> >   #include <linux/platform_device.h>
> >   #include <linux/pm_opp.h>
> > +#include <linux/pwr_domain_warming.h>
> >   #include <soc/qcom/cmd-db.h>
> >   #include <soc/qcom/rpmh.h>
> >   #include <dt-bindings/power/qcom-rpmpd.h>
> > @@ -48,6 +49,7 @@ struct rpmhpd {
> >          bool            enabled;
> >          const char      *res_name;
> >          u32             addr;
> > +       bool            is_warming_dev;
> >   };
> >
> >   struct rpmhpd_desc {
> > @@ -55,6 +57,8 @@ struct rpmhpd_desc {
> >          size_t num_pds;
> >   };
> >
> > +const struct rpmhpd_desc *global_desc;
> > +
> >   static DEFINE_MUTEX(rpmhpd_lock);
> >
> >   /* SDM845 RPMH powerdomains */
> > @@ -89,6 +93,7 @@ static struct rpmhpd sdm845_mx = {
> >          .pd = { .name = "mx", },
> >          .peer = &sdm845_mx_ao,
> >          .res_name = "mx.lvl",
> > +       .is_warming_dev = true,
> >   };
> >
> >   static struct rpmhpd sdm845_mx_ao = {
> > @@ -396,7 +401,14 @@ static int rpmhpd_probe(struct platform_device *pdev)
> >                                                 &rpmhpds[i]->pd);
> >          }
> >
> > -       return of_genpd_add_provider_onecell(pdev->dev.of_node, data);
> > +       ret = of_genpd_add_provider_onecell(pdev->dev.of_node, data);
> > +
> > +       if (ret)
> > +               return ret;
> > +
> > +       global_desc = desc;
>
> I assume this works fine, for now.
>
> Although, nothing prevents this driver from being probed for two
> different compatibles for the same platform. Thus the global_desc
> could be overwritten with the last one being probed, so then how do
> you know which one to use?

Yes. It works fine for now. There are multiple ways to fix this in 
future. One is to make global_desc an array. Other would be to move
the code in rpmhpd_init_warming_device to this init and make this a 
post_core init considering thermal subsytem uses core init. Like you 
said I will leave this at this for now and we can fix this if a need 
arises. I don't think there is a need for multiple compatibles for the 
same platform now. Thanks for the reviewed by! I will add it in the next 
version.

> > +
> > +       return 0;
> >   }
> >
> >   static struct platform_driver rpmhpd_driver = {
> > @@ -413,3 +425,27 @@ static int __init rpmhpd_init(void)
> >          return platform_driver_register(&rpmhpd_driver);
> >   }
> >   core_initcall(rpmhpd_init);
> > +
> > +static int __init rpmhpd_init_warming_device(void)
> > +{
> > +       size_t num_pds;
> > +       struct rpmhpd **rpmhpds;
> > +       int i;
> > +
> > +       if (!global_desc)
> > +               return -EINVAL;
> > +
> > +       rpmhpds = global_desc->rpmhpds;
> > +       num_pds = global_desc->num_pds;
> > +
> > +       if (!of_find_property(rpmhpds[0]->dev->of_node, "#cooling-cells", NULL))
> > +               return 0;
> > +
> > +       for (i = 0; i < num_pds; i++)
> > +               if (rpmhpds[i]->is_warming_dev)
> > +                       pwr_domain_warming_register(rpmhpds[i]->dev,
> > +                                                   rpmhpds[i]->res_name, i);
> > +
> > +       return 0;
> > +}
> > +late_initcall(rpmhpd_init_warming_device);
>
> For the record, there are limitations with this approach, for example
> you can't deal with -EPROBE_DEFER.
>
> On the other hand, I don't have anything better to suggest, from the
> top of my head. So, feel free to add:
>
> Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>
> Kind regards
> Uffe

--
Warm Regards
Thara