f07e572f64
bcm2708: boot tested on RPi B+ v1.2 bcm2709: boot tested on RPi 3B v1.2 and RPi 4B v1.1 4G bcm2710: boot tested on RPi 3B v1.2 bcm2711: boot tested on RPi 4B v1.1 4G Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
89 lines
3.1 KiB
Diff
89 lines
3.1 KiB
Diff
From aa455fdc2495cb05b65cc03cc472de43df632c5c Mon Sep 17 00:00:00 2001
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From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
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Date: Tue, 22 Oct 2019 10:36:24 +0200
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Subject: [PATCH] backlight: gpio: Explicitly set the direction of
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the GPIO
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commit 706dc68102bc7421a9e6573d149ab6d769d71cc7 upstream.
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The GPIO backlight driver currently requests the line 'as is', without
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acively setting its direction. This can lead to problems: if the line
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is in input mode by default, we won't be able to drive it later when
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updating the status and also reading its initial value doesn't make
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sense for backlight setting.
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Request the line 'as is' initially, so that we can read its value
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without affecting it but then change the direction to output explicitly
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when setting the initial brightness.
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Also: check the current direction and only read the value if it's output.
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Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
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Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
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Signed-off-by: Lee Jones <lee.jones@linaro.org>
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---
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drivers/video/backlight/gpio_backlight.c | 23 ++++++++++++++++++-----
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1 file changed, 18 insertions(+), 5 deletions(-)
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--- a/drivers/video/backlight/gpio_backlight.c
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+++ b/drivers/video/backlight/gpio_backlight.c
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@@ -26,9 +26,8 @@ struct gpio_backlight {
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int def_value;
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};
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-static int gpio_backlight_update_status(struct backlight_device *bl)
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+static int gpio_backlight_get_next_brightness(struct backlight_device *bl)
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{
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- struct gpio_backlight *gbl = bl_get_data(bl);
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int brightness = bl->props.brightness;
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if (bl->props.power != FB_BLANK_UNBLANK ||
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@@ -36,6 +35,14 @@ static int gpio_backlight_update_status(
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bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
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brightness = 0;
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+ return brightness;
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+}
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+
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+static int gpio_backlight_update_status(struct backlight_device *bl)
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+{
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+ struct gpio_backlight *gbl = bl_get_data(bl);
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+ int brightness = gpio_backlight_get_next_brightness(bl);
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+
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gpiod_set_value_cansleep(gbl->gpiod, brightness);
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return 0;
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@@ -86,7 +93,8 @@ static int gpio_backlight_initial_power_
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return gbl->def_value ? FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN;
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/* if the enable GPIO is disabled, do not enable the backlight */
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- if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
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+ if (gpiod_get_direction(gbl->gpiod) == 0 &&
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+ gpiod_get_value_cansleep(gbl->gpiod) == 0)
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return FB_BLANK_POWERDOWN;
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return FB_BLANK_UNBLANK;
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@@ -100,7 +108,7 @@ static int gpio_backlight_probe(struct p
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struct backlight_properties props;
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struct backlight_device *bl;
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struct gpio_backlight *gbl;
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- int ret;
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+ int ret, init_brightness;
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gbl = devm_kzalloc(&pdev->dev, sizeof(*gbl), GFP_KERNEL);
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if (gbl == NULL)
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@@ -153,7 +161,12 @@ static int gpio_backlight_probe(struct p
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bl->props.power = gpio_backlight_initial_power_state(gbl);
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bl->props.brightness = 1;
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- backlight_update_status(bl);
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+ init_brightness = gpio_backlight_get_next_brightness(bl);
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+ ret = gpiod_direction_output(gbl->gpiod, init_brightness);
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+ if (ret) {
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+ dev_err(&pdev->dev, "failed to set initial brightness\n");
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+ return ret;
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+ }
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platform_set_drvdata(pdev, bl);
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return 0;
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