linux-kernel - Re: [PATCH v2 7/8] arm64: dts: mediatek: cherry: Enable keyboard PWM backlight

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Message-ID: <8e47ef16-f310-2242-42c6-8081a4a33d8b@collabora.com>
Date:   Mon, 25 Jul 2022 12:14:35 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Chen-Yu Tsai <wenst@...omium.org>
Cc:     matthias.bgg@...il.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 7/8] arm64: dts: mediatek: cherry: Enable keyboard PWM
 backlight

Il 25/07/22 12:06, Chen-Yu Tsai ha scritto:
> On Mon, Jul 25, 2022 at 6:04 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@...labora.com> wrote:
>>
>> Il 25/07/22 11:57, Chen-Yu Tsai ha scritto:
>>> n Thu, Jul 21, 2022 at 10:53 PM AngeloGioacchino Del Regno
>>> <angelogioacchino.delregno@...labora.com> wrote:
>>>>
>>>> Add a pwm-leds node to enable the PWM controlled keyboard backlight.
>>>>
>>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>>>> ---
>>>>    arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi | 13 +++++++++++++
>>>>    1 file changed, 13 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>>>> index ca9955a97f8f..9086a440a995 100644
>>>> --- a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>>>> +++ b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>>>> @@ -4,6 +4,7 @@
>>>>     */
>>>>
>>>>    #include <dt-bindings/gpio/gpio.h>
>>>> +#include <dt-bindings/leds/common.h>
>>>>    #include "mt8195.dtsi"
>>>>    #include "mt6359.dtsi"
>>>>
>>>> @@ -31,6 +32,18 @@ dmic_codec: dmic-codec {
>>>>                   wakeup-delay-ms = <50>;
>>>>           };
>>>>
>>>> +       led-controller {
>>>> +               compatible = "pwm-leds";
>>>> +
>>>> +               keyboard_backlight: keyboard-backlight {
>>>> +                       default-state = "off";
>>>> +                       function = LED_FUNCTION_KBD_BACKLIGHT;
>>>> +                       label = "cros_ec::kbd_backlight";
>>>> +                       max-brightness = <1023>;
>>>> +                       pwms = <&cros_ec_pwm 3>;
>>>> +               };
>>>> +       };
>>>> +
>>>
>>> This didn't work for me. However using "google,cros-kbd-led-backlight"
>>> under the EC did. That might be a better option.
>>
>> Strange. But okay if there's a better option I'll check that out for v3.
> 
> It might be an EC firmware version issue. My devices are all running
> test images, and don't automatically update the EC firmware.
> 
> For reference, mine is at:
> 
> RO:    tomato_v2.0.10686-234e646fd8
>          tomato_14268.0.0
> RW:    tomato_v2.0.10686-234e646fd8
>          tomato_14268.0.0
> Build:    tomato_v2.0.10686-234e646fd8 tomato_14268.0.0
>          2021-10-07 09:00:32
>          @chromeos-ci-legacy-us-central2-d-x32-34-us9d
> 

It's surely about the firmware, because I can confirm that I didn't
have a working KB kacklight before upgrading... I remember debugging
that and I couldn't figure out why it wasn't working...

After an upgrade, it magically worked, so that's it.

RO version:    tomato_v2.0.11883-9f0d374060

RO cros fwid:  tomato_14454.14.0

RW version:    tomato_v2.0.11893-d27ab0e96d

RW cros fwid:  tomato_14454.23.0

That's the FW that I have here on my machine... :-)

I'll anyway check out the binding that you suggested, as if that works
in any condition that's simply better!

> ChenYu
> 
>> Cheers!
>> Angelo
>>
>>>
>>> ChenYu
>>>
>>>>           memory@...00000 {
>>>>                   device_type = "memory";
>>>>                   reg = <0 0x40000000 0 0x80000000>;
>>>> --
>>>> 2.35.1
>>>>
>>>>
>>>> _______________________________________________
>>>> linux-arm-kernel mailing list
>>>> linux-arm-kernel@...ts.infradead.org
>>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>

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