From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7AB2812B74 for ; Thu, 5 Oct 2023 20:40:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nwlPnQ1B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6401DC433C8; Thu, 5 Oct 2023 20:40:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696538449; bh=ZiSfuU42hIkri3lX6i6qYBHumLjvADyoS7eztHiRywQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=nwlPnQ1BZh93ZRxulqGf6uh1OZFga1A6nrzFv/slg6YiIbBonM9PLUy42bhBxmlNO 40eQf+Ogdbr/d+1slQxQq4WAG6k7iNWb1QjWjqoTwKQw5psHQUAQJhzJzQPHW+k0wp pOeSGEtTJGhcpB7Sj3OqEbBh6pfS9Nw24WxOTi8EhwnTnUsB3D9kpgt4sSM1uzV2rT /fkTEYoVIN4OahNKwulmzaSXRd6hwsu12mtstLMw0rFenIXiztfq47t/FWgsVWovPk NKLaT+PQJjseqCibht83I5ary+udGCn18wwPJtUe8ujELVbCWPthpWe//C6SMs51Xl iegzjaAZqL8Iw== Message-ID: Date: Thu, 5 Oct 2023 22:40:41 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] backlight: Add Kinetic KTD2801 driver To: =?UTF-8?Q?Duje_Mihanovi=C4=87?= , Lee Jones , Daniel Thompson , Jingoo Han , Pavel Machek , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Helge Deller Cc: Karel Balej , dri-devel@lists.freedesktop.org, linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, ~postmarketos/upstreaming@lists.sr.ht References: <20231005-ktd2801-v1-0-43cd85b0629a@skole.hr> <20231005-ktd2801-v1-2-43cd85b0629a@skole.hr> Content-Language: en-US From: Krzysztof Kozlowski Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 05/10/2023 20:49, Duje Mihanović wrote: > Add driver for the Kinetic KTD2801 backlight driver. > > Signed-off-by: Duje Mihanović > --- > MAINTAINERS | 6 ++ > drivers/video/backlight/Kconfig | 7 ++ > drivers/video/backlight/Makefile | 1 + > drivers/video/backlight/ktd2801-backlight.c | 151 ++++++++++++++++++++++++++++ > 4 files changed, 165 insertions(+) ... > + > +#define EW_DELAY 150 > +#define EW_DET 270 > +#define LOW_BIT_HIGH 5 > +#define LOW_BIT_LOW (4 * HIGH_BIT_LOW) > +#define HIGH_BIT_LOW 5 > +#define HIGH_BIT_HIGH (4 * HIGH_BIT_LOW) > +#define DS 5 > +#define EOD_L 10 > +#define EOD_H 350 > +#define PWR_DOWN_DELAY 2600 > + > +#define KTD2801_DEFAULT_BRIGHTNESS 100 > +#define KTD2801_MAX_BRIGHTNESS 255 > + > +struct ktd2801_backlight { > + struct device *dev; > + struct backlight_device *bd; > + struct gpio_desc *desc; s/desc/enable_gpio/ or something similar. desc is totally not related. > + bool was_on; > +}; > + > +static int ktd2801_update_status(struct backlight_device *bd) > +{ > + struct ktd2801_backlight *ktd2801 = bl_get_data(bd); > + u8 brightness = (u8) backlight_get_brightness(bd); > + > + if (backlight_is_blank(bd)) { > + gpiod_set_value(ktd2801->desc, 1); > + udelay(PWR_DOWN_DELAY); > + ktd2801->was_on = false; > + return 0; > + } > + > + if (!ktd2801->was_on) { > + gpiod_set_value(ktd2801->desc, 0); > + udelay(EW_DELAY); > + gpiod_set_value(ktd2801->desc, 1); > + udelay(EW_DET); > + gpiod_set_value(ktd2801->desc, 0); > + ktd2801->was_on = true; > + } > + > + gpiod_set_value(ktd2801->desc, 0); > + udelay(DS); > + > + for (int i = 0; i < 8; i++) { > + u8 next_bit = (brightness & 0x80) >> 7; > + > + if (!next_bit) { > + gpiod_set_value(ktd2801->desc, 1); > + udelay(LOW_BIT_LOW); > + gpiod_set_value(ktd2801->desc, 0); > + udelay(LOW_BIT_HIGH); > + } else { > + gpiod_set_value(ktd2801->desc, 1); > + udelay(HIGH_BIT_LOW); > + gpiod_set_value(ktd2801->desc, 0); > + udelay(HIGH_BIT_HIGH); > + } > + brightness <<= 1; > + } > + gpiod_set_value(ktd2801->desc, 1); > + udelay(EOD_L); > + gpiod_set_value(ktd2801->desc, 0); > + udelay(EOD_H); Hm, why device is kept off after this? Setting 0 means enable GPIO is logical 0. > + return 0; > +} > + > +static const struct backlight_ops ktd2801_backlight_ops = { > + .update_status = ktd2801_update_status, > +}; > + > +static int ktd2801_backlight_probe(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct backlight_device *bd; > + struct ktd2801_backlight *ktd2801; > + u32 brightness, max_brightness; > + int ret; > + > + ktd2801 = devm_kzalloc(dev, sizeof(*ktd2801), GFP_KERNEL); > + if (!ktd2801) > + return -ENOMEM; > + ktd2801->dev = dev; > + ktd2801->was_on = true; > + > + ret = device_property_read_u32(dev, "max-brightness", &max_brightness); > + if (ret) > + max_brightness = KTD2801_MAX_BRIGHTNESS; > + if (max_brightness > KTD2801_MAX_BRIGHTNESS) { > + dev_err(dev, "illegal max brightness specified\n"); > + max_brightness = KTD2801_MAX_BRIGHTNESS; > + } > + > + ret = device_property_read_u32(dev, "default-brightness", &brightness); > + if (ret) > + brightness = KTD2801_DEFAULT_BRIGHTNESS; > + if (brightness > max_brightness) { > + dev_err(dev, "default brightness exceeds max\n"); > + brightness = max_brightness; > + } > + > + ktd2801->desc = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW); OUT_LOW is keep it disabled, so is this intentional? > + if (IS_ERR(ktd2801->desc)) > + return dev_err_probe(dev, PTR_ERR(ktd2801->desc), > + "failed to get backlight GPIO"); > + gpiod_set_consumer_name(ktd2801->desc, dev_name(dev)); > + > + bd = devm_backlight_device_register(dev, dev_name(dev), dev, ktd2801, > + &ktd2801_backlight_ops, NULL); > + if (IS_ERR(bd)) > + return dev_err_probe(dev, PTR_ERR(bd), > + "failed to register backlight"); > + > + bd->props.max_brightness = max_brightness; > + bd->props.brightness = brightness; > + > + ktd2801->bd = bd; > + platform_set_drvdata(pdev, bd); > + backlight_update_status(bd); > + > + return 0; > +} > + > +static const struct of_device_id ktd2801_of_match[] = { > + { .compatible = "kinetic,ktd2801" }, > + { } > +}; > +MODULE_DEVICE_TABLE(of, ktd2801_of_match); > + > +static struct platform_driver ktd2801_backlight_driver = { > + .driver = { > + .name = "ktd2801-backlight", > + .of_match_table = ktd2801_of_match, > + }, > + .probe = ktd2801_backlight_probe, > +}; > +module_platform_driver(ktd2801_backlight_driver); > + > +MODULE_AUTHOR("Duje Mihanović "); > +MODULE_DESCRIPTION("Kinetic KTD2801 Backlight Driver"); > +MODULE_LICENSE("GPL"); > +MODULE_ALIAS("platform:ktd2801-backlight"); You should not need MODULE_ALIAS() in normal cases. If you need it, usually it means your device ID table is wrong. > Best regards, Krzysztof