linux-kernel - Re: [PATCH v5 13/13] video: backlight: mt6370: Add MediaTek MT6370 support

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Message-ID: <ec3bdfb8-0e42-a772-28b1-165811872afa@collabora.com>
Date:   Fri, 15 Jul 2022 14:38:45 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     ChiaEn Wu <peterwu.pub@...il.com>, lee.jones@...aro.org,
        daniel.thompson@...aro.org, jingoohan1@...il.com, pavel@....cz,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        matthias.bgg@...il.com, sre@...nel.org, chunfeng.yun@...iatek.com,
        gregkh@...uxfoundation.org, jic23@...nel.org, lars@...afoo.de,
        lgirdwood@...il.com, broonie@...nel.org, linux@...ck-us.net,
        heikki.krogerus@...ux.intel.com, deller@....de
Cc:     chiaen_wu@...htek.com, alice_chen@...htek.com,
        cy_huang@...htek.com, dri-devel@...ts.freedesktop.org,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-iio@...r.kernel.org, linux-fbdev@...r.kernel.org,
        szunichen@...il.com
Subject: Re: [PATCH v5 13/13] video: backlight: mt6370: Add MediaTek MT6370
 support

Il 15/07/22 13:26, ChiaEn Wu ha scritto:
> From: ChiaEn Wu <chiaen_wu@...htek.com>
> 
> MediaTek MT6370 is a SubPMIC consisting of a single cell battery charger
> with ADC monitoring, RGB LEDs, dual channel flashlight, WLED backlight
> driver, display bias voltage supply, one general purpose LDO, and the
> USB Type-C & PD controller complies with the latest USB Type-C and PD
> standards.
> 
> This adds support for MediaTek MT6370 Backlight driver. It's commonly used
> to drive the display WLED. There are 4 channels inside, and each channel
> supports up to 30mA of current capability with 2048 current steps in
> exponential or linear mapping curves.
> 
> Signed-off-by: ChiaEn Wu <chiaen_wu@...htek.com>

Hello ChiaEn,

I propose to move this one to drivers/leds (or drivers/pwm) and, instead of
registering a backlight device, register a PWM device.

This way you will be able to reuse the generic backlight-pwm driver, as you'd
be feeding the PWM device exposed by this driver to the generic one: this will
most importantly make it easy to chain it with MTK_DISP_PWM (mtk-pwm-disp)
with a devicetree that looks like...

	pwmleds-disp {

		compatible = "pwm-leds";



		disp_led: disp-pwm {

			label = "backlight-pwm";

			pwms = <&pwm0 0 500000>;

			max-brightness = <1024>;

		};

	};



	backlight_lcd0: backlight {

		compatible = "led-backlight";

		leds = <&disp_led>, <&pmic_bl_led>;



		default-brightness-level = <300>;

	};

Regards,
Angelo