Re: [PATCH v3 3/3] leds: tps68470: Add LED control for tps68470

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On Thu 2023-03-23 12:29:29, Hans de Goede wrote:
> Hi,
> 
> On 3/23/23 12:26, Pavel Machek wrote:
> > On Thu 2023-03-23 12:24:05, Hans de Goede wrote:
> >> Hi Pavel,
> >>
> >> On 3/23/23 12:15, Pavel Machek wrote:
> >>> Hi!
> >>>
> >>>> There are two LED controllers, LEDA indicator LED and LEDB flash LED for
> >>>> tps68470. LEDA can be enabled by setting TPS68470_ILEDCTL_ENA. Moreover,
> >>>> tps68470 provides four levels of power status for LEDB. If the
> >>>> properties called "ti,ledb-current" can be found, the current will be
> >>>> set according to the property values. These two LEDs can be controlled
> >>>> through the LED class of sysfs (tps68470-leda and tps68470-ledb).
> >>>
> >>> If the LED can have four different currents, should it have 4
> >>> brightness levels?
> >>
> >> No this was already discussed with an earlier version. This is in
> >> indicator LED output. The current setting is a one time boot configure
> >> thing after which the indicator LED is either on or off.
> > 
> > Current levels are exponential in that driver. That will result in
> > rather nice four level. Surely LED does not care if you set it during
> > boot or later?
> 
> Well for one there is no guarantee the LED can continuously handle
> the maximum configurable LED current and as you rightly point out
> elsewhere in the thread we don't want to be blowing up hw.

hw can support 16mA -> you expose 0, 2mA, 4mA, 8mA, 16mA levels.

hw can support 4mA -> you expose 0, 2mA, 4mA.

Triggers will work with these.

Best regards,
								Pavel
-- 
People of Russia, stop Putin before his war on Ukraine escalates.

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