[PATCH 2/2] ARM: dts: exynos: arndale: fix HDMI-HPD line handling

[Krzysztof Kozlowski]

On 26 July 2018 at 13:50, Andrzej Hajda <a.hajda at samsung.com> wrote:
> On 26.07.2018 12:44, Krzysztof Kozlowski wrote:
>> On 26 July 2018 at 12:12, Andrzej Hajda <a.hajda at samsung.com> wrote:
>>> HDMI-HPD was set active low, moreover by default pincontrol
>>> chip sets pull-down on the pin. As a result HDMI driver
>>> assumes TV is always connected regardless of actual state.
>>> The patch fixes it.
>>>
>>> Signed-off-by: Andrzej Hajda <a.hajda at samsung.com>
>>> ---
>>>  arch/arm/boot/dts/exynos5250-arndale.dts  | 4 +++-
>>>  arch/arm/boot/dts/exynos5250-pinctrl.dtsi | 5 +++++
>>>  2 files changed, 8 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/boot/dts/exynos5250-arndale.dts b/arch/arm/boot/dts/exynos5250-arndale.dts
>>> index 591023391f7d..26bae5157177 100644
>>> --- a/arch/arm/boot/dts/exynos5250-arndale.dts
>>> +++ b/arch/arm/boot/dts/exynos5250-arndale.dts
>>> @@ -210,9 +210,11 @@
>>>  };
>>>
>>>  &hdmi {
>>> +       pinctrl-names = "default";
>>> +       pinctrl-0 = <&hdmi_hpd>;
>>>         status = "okay";
>>>         ddc = <&i2c_ddc>;
>>> -       hpd-gpios = <&gpx3 7 GPIO_ACTIVE_LOW>;
>>> +       hpd-gpios = <&gpx3 7 GPIO_ACTIVE_HIGH>;
>> The gpx3-7 (HDMI-HPD) has external pull up to... so maybe it should be
>> active low? How can it go high if it is already high?
>> I am not sure if this matters because the driver ignores the flags and
>> responds on both falling and rising edge.
>
> HDMI specification says HPD is active high!
> Arndale schematics are quite misleading - pull-up resistors near level
> shifter are marked as not-connected :) so there are no pull-ups.
> And there is pull-down resistor on right side of the level shifter.

Ah, I was looking at schematics and looking and looking and still did
not see "NC"... My mistake.

> And finally with this patch it works as expected, without it it works
> sometimes.

Everything is good. I already sent last pull request so this will go
after merge window, for v4.20 (or whatever number it will be).

Best regards,
Krzysztof