On 06/20/2014 02:26 PM, Alexandre Courbot wrote:
On 06/20/2014 02:56 AM, Mark Brown wrote:
* PGP Signed by an unknown key
On Thu, Jun 19, 2014 at 09:59:04AM -0600, Stephen Warren wrote:
On 06/19/2014 01:49 AM, Alexandre Courbot wrote:
Remove the regulator-always-on property from some regulators that do
not
need it. On recent kernels fixed regulators which supply is always on
fail registration.
That sounds like a bug in the regulator core, which should be fixed
there.
Please actually describe the problem you believe you are seeing - I've
seen no reports and I can't tell anything from what you've described,
nor can I see any obvious way that a regulator being fixed would have
any effect on its supply.
Here is some more information about what happens.
We have a fixed regulator defined as follows:
vdd_lcd: regulator@2 {
compatible = "regulator-fixed";
reg = <2>;
regulator-name = "VD_LCD_1V8";
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
gpio = <&palmas_gpio 4 GPIO_ACTIVE_HIGH>;
enable-active-high;
vin-supply = <&vdd_1v8>;
regulator-boot-on;
};
Its vin-supply is part of the palmas device:
vdd_1v8: smps8 {
regulator-name = "vs-pmu-1v8";
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
regulator-always-on;
regulator-boot-on;
};
When vdd_lcd is registered, set_supply() is called, which creates a new
regulator for vdd_1v8. In create_regulator(),
_regulator_can_change_status() returns false (as it should since the
regulator is always_on) and _regulator_is_enabled() *also* returns
false, so as a result regulator->always_on remains false for vdd_1v8.
Later in regulator_register(), we try to enable the supply. Since
regulator->always_on is false, _regulator_enable() is called on vdd_1v8,
and the pair _regulator_is_enabled() / _regulator_can_change_status() is
called again with the same result, which causes _regulator_enable() to
return -EPERM. This prevents vdd_lcd from being registered.
So I can see three questions here:
1) Why does _regulator_enable() on vdd_1v8 return 0 while everything
suggests that it is enabled (this regulator powers lot of devices, like
eMMC, which are working fine). This may be an issue with the palmas driver.
Ran a bisect eventually, found that reverting this commit led to SMPS8's
enabled status to be properly reported at boot time (and consequently
the register probe to succeed):
dbabd624d
regulator: palmas: Reemove open coded functions with helper functions
Keerthy, Nishanth, could it be that there is still something wrong with
the REGULATOR_LINEAR_RANGE() definitions?
This seems to be the cause for our trouble, but the other questions
might still stand, in case there is interest in discussing them.
2) When an always-on regulator that is not yet enabled is registered,
shouldn't it be switched on by the regulator framework?
3) When a boot-on regulator is registered and _regulator_is_enabled()
returns contradictory information, what should be done?
Note that whether the regulator-boot-on property is present or not does
not change anything.
I tried to find a recent patch that could have introduced a change of
behavior, but could not find anything so far. Bisecting is made harder
by the fact this happens on a newly-introduced board which requires a
bunch of patches of its own, but it we need more information I can try
to do it anyway.
Thanks,
Alex.
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