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SubjectRe: [PATCH v10 4/8] drm/ingenic: Add dw-hdmi driver for jz4780
Hi Nikolaus, Mark,

Le mer., déc. 1 2021 at 14:51:51 +0100, H. Nikolaus Schaller
<hns@goldelico.com> a écrit :
> Hi,
>
>> Am 01.12.2021 um 14:39 schrieb Mark Brown <broonie@kernel.org>:
>>
>> 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.

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
>
>
>
>


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