Hi Paul,
> Am 01.12.2021 um 15:03 schrieb Paul Cercueil <paul@xxxxxxxxxxxxxxx>:
>
> Hi Nikolaus, Mark,
>
> Le mer., déc. 1 2021 at 14:51:51 +0100, H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> a écrit :
>> Hi,
>>> Am 01.12.2021 um 14:39 schrieb Mark Brown <broonie@xxxxxxxxxx>:
>>> On Wed, Dec 01, 2021 at 01:02:45PM +0000, Paul Cercueil wrote:
>>>> Le mar., nov. 30 2021 at 22:26:37 +0100, H. Nikolaus Schaller
>>>>> + regulator = devm_regulator_get_optional(&pdev->dev, "hdmi-5v");
>>>>> + if (IS_ERR(regulator)) {
>>>>> + ret = PTR_ERR(regulator);
>>> Why is this using _optional()? This should only be done when the supply
>>> can be physically absent
>> There can be +5V for HDMI but without a regulator that is visible to or controllable
>> by the driver.
>
> There is always a power supply though. Either a controllable one (through e.g. a GPIO), or it's just connected to the mains +5V; the pin is never left floating. In the second case, in DTS the "hdmi-5v" would be connected to some 5v regulator, even if it's just a dummy VCC-5V regulator. So Mark has a point.
>
>> So hdmi-5v can be simply missing in DTS in which case the driver does not need to
>> care about. The driver just can't turn it on or off.
>
> Please make it mandatory in DTS then, and use devm_regulator_get() in the driver.
Well, I just wonder why the elegant devm_regulator_get_optional() exists at all
and seems to be used in ca. 80 places.
And if it is not allowed, why some DTS should be forced to add not physically existing dummy-regulators.
AFAIR drivers should implement functionality defined by DTS but not the other way round: enforce DTS style.
BTW: there is no +5 mains dummy regulator defined in ci20.dts.
What I fear is that if we always have to define the mains +5V (which is for example not
defined in ci20.dts), which rules stops us from asking to add a dummy-regulator from 110/230V to +5V as well.
In last consequence, it seems as if we have to describe all dummy regulators from the power plant to our hdmi-5v :)
Since I always follow the KISS principle I tend to leave out what is not relevant...
Of course adding a dummy regulator to the DTS allows to avoid the NULL pointer test
in the driver code.
Anyways, you are maintainers :)
So should I spin a v11 for the series or just this patch or how should we do it?
BR and thanks,
Nikolaus
>
> Cheers,
> -Paul
>
>>> (in which case I'd expect to see special
>>> handling).
>> The special case is to not enable/disable the regulator if it does not exist
>> and assume that there is hardware providing it otherwise (the driver can't know
>> that except by using get_optional). This is done by the code below
>>>>> + if (IS_ERR(regulator)) {
>> ...
>>> + if (!regulator)
>>> + return 0;
>>> + ret = regulator_enable(regulator);
>> ...
>> BR and thanks,
>> Nikolaus
>
>
