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

[Svyatoslav]

27 червня 2024 р. 11:48:46 GMT+03:00, Caleb Connolly <caleb.connolly at linaro.org> написав(-ла):
>
>
>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.
>> 
>> Also this seems to happen in SPL and again pre-reloc and again in
>> U-Boot post-reloc?

Not so long ago I proposed a similar patchset with the same goal
and I have discovered massive issues with SPL and relocation
interfering with driver loading. 

The issue which I have personally encountered was i2c driver failure
due to double probing. This behavior was triggered by
always-on/boot-on regulators provided by pmic which in most
cases is an i2c device.

At that time everyone just ignored me, so idk if tegra i2c is the only
driver which has this response or there are more, but be aware that
this patch set may cause cascade failure on many devices.

Best regards,
Svyatoslav R.

>> 
>> Should we have a step in the init sequence where we set up the
>> regulators, by calling regulators_enable_boot_on() ?
>> 
>> Regards,
>> Simon
>