Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <ec3bdfb8-0e42-a772-28b1-165811872afa@collabora.com>
Date:   Fri, 15 Jul 2022 14:38:45 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.11.0
Subject: Re: [PATCH v5 13/13] video: backlight: mt6370: Add MediaTek MT6370
 support
Content-Language: en-US
To:     ChiaEn Wu <peterwu.pub@gmail.com>, lee.jones@linaro.org,
        daniel.thompson@linaro.org, jingoohan1@gmail.com, pavel@ucw.cz,
        robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        matthias.bgg@gmail.com, sre@kernel.org, chunfeng.yun@mediatek.com,
        gregkh@linuxfoundation.org, jic23@kernel.org, lars@metafoo.de,
        lgirdwood@gmail.com, broonie@kernel.org, linux@roeck-us.net,
        heikki.krogerus@linux.intel.com, deller@gmx.de
Cc:     chiaen_wu@richtek.com, alice_chen@richtek.com,
        cy_huang@richtek.com, dri-devel@lists.freedesktop.org,
        linux-leds@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-iio@vger.kernel.org, linux-fbdev@vger.kernel.org,
        szunichen@gmail.com
References: <20220715112607.591-1-peterwu.pub@gmail.com>
 <20220715112607.591-14-peterwu.pub@gmail.com>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
In-Reply-To: <20220715112607.591-14-peterwu.pub@gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

Il 15/07/22 13:26, ChiaEn Wu ha scritto:
> From: ChiaEn Wu <chiaen_wu@richtek.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@richtek.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