linux-kernel - [PATCH v3 3/4] backlight: pwm_bl: Set scale type for CIE 1931 curves

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Message-Id: <20190709190007.91260-4-mka@chromium.org>
Date:   Tue,  9 Jul 2019 12:00:06 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Thierry Reding <thierry.reding@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc:     linux-pwm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Douglas Anderson <dianders@...omium.org>,
        Brian Norris <briannorris@...omium.org>,
        Pavel Machek <pavel@....cz>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Matthias Kaehlcke <mka@...omium.org>
Subject: [PATCH v3 3/4] backlight: pwm_bl: Set scale type for CIE 1931 curves

For backlight curves calculated with the CIE 1931 algorithm set
the brightness scale type to non-linear. This makes the scale type
available to userspace via the 'scale' sysfs attribute.

Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
Tested-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
Acked-by: Daniel Thompson <daniel.thompson@...aro.org>
---
Changes in v3:
- mark scale as non-linear instead of using the CIE1931 type which
  has been removed
- updated commit message

Changes in v2:
- added Enric's 'Tested-by' tag
- added Daniel's 'Acked-by' tag
---
 drivers/video/backlight/pwm_bl.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index fb45f866b923..7c6dfc4a601d 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -553,6 +553,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 		goto err_alloc;
 	}
 
+	memset(&props, 0, sizeof(struct backlight_properties));
+
 	if (data->levels) {
 		/*
 		 * For the DT case, only when brightness levels is defined
@@ -591,6 +593,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 
 			pb->levels = data->levels;
 		}
+
+		props.scale = BACKLIGHT_SCALE_NON_LINEAR;
 	} else {
 		/*
 		 * That only happens for the non-DT case, where platform data
@@ -601,7 +605,6 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 
 	pb->lth_brightness = data->lth_brightness * (state.period / pb->scale);
 
-	memset(&props, 0, sizeof(struct backlight_properties));
 	props.type = BACKLIGHT_RAW;
 	props.max_brightness = data->max_brightness;
 	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
-- 
2.22.0.410.gd8fdbe21b5-goog