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From: Daniel Thompson <daniel.thompson@linaro.org>
To: Luca Weiss <luca@z3ntu.xyz>
Cc: ~postmarketos/upstreaming@lists.sr.ht,
	phone-devel@vger.kernel.org, Lee Jones <lee@kernel.org>,
	Jingoo Han <jingoohan1@gmail.com>, Helge Deller <deller@gmx.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	"G.Shark Jeong" <gshark.jeong@gmail.com>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Maximilian Weigand <mweigand@mweigand.net>,
	dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	devicetree@vger.kernel.org
Subject: Re: [PATCH 3/4] backlight: lm3630a: Use backlight_get_brightness helper in update_status
Date: Tue, 20 Feb 2024 14:11:07 +0000	[thread overview]
Message-ID: <20240220141107.GF6716@aspen.lan> (raw)
In-Reply-To: <20240220-lm3630a-fixups-v1-3-9ca62f7e4a33@z3ntu.xyz>

On Tue, Feb 20, 2024 at 12:11:21AM +0100, Luca Weiss wrote:
> As per documentation "drivers are expected to use this function in their
> update_status() operation to get the brightness value.".
>
> With this we can also drop the manual backlight_is_blank() handling
> since backlight_get_brightness() is already handling this correctly.
>
> Signed-off-by: Luca Weiss <luca@z3ntu.xyz>

Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>

However...

> ---
>  	/* disable sleep */
> @@ -201,9 +202,9 @@ static int lm3630a_bank_a_update_status(struct backlight_device *bl)
>  		goto out_i2c_err;
>  	usleep_range(1000, 2000);
>  	/* minimum brightness is 0x04 */
> -	ret = lm3630a_write(pchip, REG_BRT_A, bl->props.brightness);
> +	ret = lm3630a_write(pchip, REG_BRT_A, brightness);

... then handling of the minimum brightness looks weird in this driver.

The range of the backlight is 0..max_brightness. Sadly the drivers
are inconsistant regarding whether zero means off or just minimum,
however three certainly isn't supposed to mean off! In other words the
offsetting should be handled by driver rather than hoping userspace has
some magic LM3630A mode.

You didn't introduce this so this patch still has my R-b ...


Daniel.

  reply	other threads:[~2024-02-20 14:11 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-19 23:11 [PATCH 0/4] Various fixes for the lm3630a backlight driver Luca Weiss
2024-02-19 23:11 ` [PATCH 1/4] backlight: lm3630a: Initialize backlight_properties on init Luca Weiss
2024-02-20 14:00   ` Daniel Thompson
2024-02-20 14:07   ` Konrad Dybcio
2024-02-20 15:41     ` Daniel Thompson
2024-02-19 23:11 ` [PATCH 2/4] backlight: lm3630a: Don't set bl->props.brightness in get_brightness Luca Weiss
2024-02-20 14:03   ` Daniel Thompson
2024-02-19 23:11 ` [PATCH 3/4] backlight: lm3630a: Use backlight_get_brightness helper in update_status Luca Weiss
2024-02-20 14:11   ` Daniel Thompson [this message]
2024-02-20 16:43     ` Luca Weiss
2024-02-21 11:20       ` Daniel Thompson
2024-02-19 23:11 ` [PATCH 4/4] ARM: dts: qcom: msm8974-hammerhead: Hook up backlight Luca Weiss
2024-02-20 14:12   ` Daniel Thompson
2024-02-20 16:45     ` Luca Weiss
2024-02-20 17:07       ` Daniel Thompson
2024-02-23 17:02 ` (subset) [PATCH 0/4] Various fixes for the lm3630a backlight driver Lee Jones

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