[PATCH 1/4] power: regulator: Trigger probe of regulators which are always-on or boot-on

[Simon Glass]

Hi Caleb,

On Fri, 28 Jun 2024 at 01:09, Caleb Connolly <caleb.connolly at linaro.org> wrote:
>
>
>
> On 27/06/2024 11:26, Simon Glass wrote:
> > Hi Caleb,
> >
> > On Thu, 27 Jun 2024 at 09:48, Caleb Connolly <caleb.connolly at linaro.org> wrote:
> >>
> >>
> >>
> >> On 27/06/2024 10:37, Simon Glass wrote:
> >>> Hi Marek,
> >>>
> >>> On Thu, 27 Jun 2024 at 00:57, Marek Vasut <marex at denx.de> wrote:
> >>>>
> >>>> In case a regulator DT node contains regulator-always-on or regulator-boot-on
> >>>> property, make sure the regulator gets correctly configured by U-Boot on start
> >>>> up. Unconditionally probe such regulator drivers. This is a preparatory patch
> >>>> for introduction of .regulator_post_probe() which would trigger the regulator
> >>>> configuration.
> >>>>
> >>>> Parsing of regulator-always-on and regulator-boot-on DT property has been
> >>>> moved to regulator_post_bind() as the information is required early, the
> >>>> rest of the DT parsing has been kept in regulator_pre_probe() to avoid
> >>>> slowing down the boot process.
> >>>>
> >>>> Signed-off-by: Marek Vasut <marex at denx.de>
> >>>> ---
> >>>> Cc: Ben Wolsieffer <benwolsieffer at gmail.com>
> >>>> Cc: Caleb Connolly <caleb.connolly at linaro.org>
> >>>> Cc: Chris Morgan <macromorgan at hotmail.com>
> >>>> Cc: Dragan Simic <dsimic at manjaro.org>
> >>>> Cc: Eugen Hristev <eugen.hristev at collabora.com>
> >>>> Cc: Francesco Dolcini <francesco.dolcini at toradex.com>
> >>>> Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
> >>>> Cc: Jaehoon Chung <jh80.chung at samsung.com>
> >>>> Cc: Jagan Teki <jagan at amarulasolutions.com>
> >>>> Cc: Jonas Karlman <jonas at kwiboo.se>
> >>>> Cc: Kever Yang <kever.yang at rock-chips.com>
> >>>> Cc: Kostya Porotchkin <kostap at marvell.com>
> >>>> Cc: Matteo Lisi <matteo.lisi at engicam.com>
> >>>> Cc: Mattijs Korpershoek <mkorpershoek at baylibre.com>
> >>>> Cc: Max Krummenacher <max.krummenacher at toradex.com>
> >>>> Cc: Neil Armstrong <neil.armstrong at linaro.org>
> >>>> Cc: Patrice Chotard <patrice.chotard at foss.st.com>
> >>>> Cc: Patrick Delaunay <patrick.delaunay at foss.st.com>
> >>>> Cc: Philipp Tomsich <philipp.tomsich at vrull.eu>
> >>>> Cc: Quentin Schulz <quentin.schulz at cherry.de>
> >>>> Cc: Sam Day <me at samcday.com>
> >>>> Cc: Simon Glass <sjg at chromium.org>
> >>>> Cc: Sumit Garg <sumit.garg at linaro.org>
> >>>> Cc: Svyatoslav Ryhel <clamor95 at gmail.com>
> >>>> Cc: Thierry Reding <treding at nvidia.com>
> >>>> Cc: Tom Rini <trini at konsulko.com>
> >>>> Cc: Volodymyr Babchuk <Volodymyr_Babchuk at epam.com>
> >>>> Cc: u-boot-amlogic at groups.io
> >>>> Cc: u-boot-qcom at groups.io
> >>>> Cc: u-boot at dh-electronics.com
> >>>> Cc: u-boot at lists.denx.de
> >>>> Cc: uboot-stm32 at st-md-mailman.stormreply.com
> >>>> ---
> >>>>    drivers/power/regulator/regulator-uclass.c | 22 +++++++++++++++-------
> >>>>    1 file changed, 15 insertions(+), 7 deletions(-)
> >>>>
> >>>> diff --git a/drivers/power/regulator/regulator-uclass.c b/drivers/power/regulator/regulator-uclass.c
> >>>> index 66fd531da04..ccc4ef33d83 100644
> >>>> --- a/drivers/power/regulator/regulator-uclass.c
> >>>> +++ b/drivers/power/regulator/regulator-uclass.c
> >>>> @@ -433,6 +433,8 @@ static int regulator_post_bind(struct udevice *dev)
> >>>>           const char *property = "regulator-name";
> >>>>
> >>>>           uc_pdata = dev_get_uclass_plat(dev);
> >>>> +       uc_pdata->always_on = dev_read_bool(dev, "regulator-always-on");
> >>>> +       uc_pdata->boot_on = dev_read_bool(dev, "regulator-boot-on");
> >>>>
> >>>>           /* Regulator's mandatory constraint */
> >>>>           uc_pdata->name = dev_read_string(dev, property);
> >>>> @@ -444,13 +446,21 @@ static int regulator_post_bind(struct udevice *dev)
> >>>>                           return -EINVAL;
> >>>>           }
> >>>>
> >>>> -       if (regulator_name_is_unique(dev, uc_pdata->name))
> >>>> -               return 0;
> >>>> +       if (!regulator_name_is_unique(dev, uc_pdata->name)) {
> >>>> +               debug("'%s' of dev: '%s', has nonunique value: '%s\n",
> >>>> +                     property, dev->name, uc_pdata->name);
> >>>> +               return -EINVAL;
> >>>> +       }
> >>>>
> >>>> -       debug("'%s' of dev: '%s', has nonunique value: '%s\n",
> >>>> -             property, dev->name, uc_pdata->name);
> >>>> +       /*
> >>>> +        * In case the regulator has regulator-always-on or
> >>>> +        * regulator-boot-on DT property, trigger probe() to
> >>>> +        * configure its default state during startup.
> >>>> +        */
> >>>> +       if (uc_pdata->always_on && uc_pdata->boot_on)
> >>>> +               dev_or_flags(dev, DM_FLAG_PROBE_AFTER_BIND);
> >>>>
> >>>> -       return -EINVAL;
> >>>> +       return 0;
> >>>>    }
> >>>>
> >>>>    static int regulator_pre_probe(struct udevice *dev)
> >>>> @@ -473,8 +483,6 @@ static int regulator_pre_probe(struct udevice *dev)
> >>>>                                                   -ENODATA);
> >>>>           uc_pdata->max_uA = dev_read_u32_default(dev, "regulator-max-microamp",
> >>>>                                                   -ENODATA);
> >>>> -       uc_pdata->always_on = dev_read_bool(dev, "regulator-always-on");
> >>>> -       uc_pdata->boot_on = dev_read_bool(dev, "regulator-boot-on");
> >>>>           uc_pdata->ramp_delay = dev_read_u32_default(dev, "regulator-ramp-delay",
> >>>>                                                       0);
> >>>>           uc_pdata->force_off = dev_read_bool(dev, "regulator-force-boot-off");
> >>>> --
> >>>> 2.43.0
> >>>>
> >>>
> >>> This is reading a lot of DT stuff very early, which may be slow. It is
> >>> also reading from the DT in the bind() step which we sometimes have to
> >>> do, but try to avoid.
> >>
> >> Could we set up the livetree pre-bind? What about MMU? On armv8 at least
> >> this would have a huge impact on performance. I've done some
> >> measurements and there is at least 1 order of magnitude difference
> >> between parsing FDT with no caches vs parsing livetree with, it's huge.
> >
> > That seems like a great idea to me, in general. The fact that SPL sets
> > up the MMU on armv8 makes it more practical.
>
> Well, on qcom we don't use SPL (yet?), we did have a cyclical dependency
> since we rely on DTB for the memory layout, although I have some patches
> to do all the memory parsing in board_fdt_blob_setup() since that's
> needed for multi-dtb FIT. So I guess we could enable caches at the same
> time.

Yes...it seems that enabling cache in SPL has become common on armv8.

As to the memory layout, I'm not sure what is happening there, but it
seems that the DT does not describe it in general (at least not until
U-Boot adds the nodes).

> >
> > But for this series I believe we are going to have to define what
> > happens in what phase. We have power_init_board() which is the old way
> > of doing this...but perhaps we could use that as a way to start up
> > regulators which are needed.
> >
> > As to my question about whether this happens in SPL / pre-reloc /
> > proper, I forgot that we have the bootph tags for that, so it should
> > be fine. The main issue is that in U-Boot proper we will re-init the
> > regulators even though that has already been done. Probably that can
> > be handled by Kconfig or a flag in SPL handoff.
>
> Ensuring that it isn't done multiple times sounds like the right
> approach to me.

OK...I wonder how we can solve this. Needs some though.


> >
> >
> >>>
> >>> Also this seems to happen in SPL and again pre-reloc and again in
> >>> U-Boot post-reloc?
> >>>
> >>> Should we have a step in the init sequence where we set up the
> >>> regulators, by calling regulators_enable_boot_on() ?

Regards,
Simon