diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.19/950-0255-gpio-ir-change-default-pull-configuration-to-up.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.19/950-0255-gpio-ir-change-default-pull-configuration-to-up.patch | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.19/950-0255-gpio-ir-change-default-pull-configuration-to-up.patch b/target/linux/brcm2708/patches-4.19/950-0255-gpio-ir-change-default-pull-configuration-to-up.patch new file mode 100644 index 0000000000..40bfc01441 --- /dev/null +++ b/target/linux/brcm2708/patches-4.19/950-0255-gpio-ir-change-default-pull-configuration-to-up.patch @@ -0,0 +1,47 @@ +From d1cf5fb57ee5ee4512a93614d67d15af9c8070b2 Mon Sep 17 00:00:00 2001 +From: Matthias Reichl <hias@horus.com> +Date: Wed, 9 Jan 2019 14:51:01 +0100 +Subject: [PATCH] gpio-ir: change default pull configuration to up + +IR receivers like the TSOP series from Vishay and compatible ones +have active-low open collector outputs with an internal pull up of +about 30k (according to the TSOP datasheets). + +Activating a pull-down resistor on the GPIO will make it work against +the pull-up in the IR receiver and brings the idle input voltage down +to about 1.9V (measured on a RPi3B+ with a TSOP4438). While that's +usually enough to make the RPi see a high signal it's certainly not +optimal and may even fail when using an IR receiver with a weaker pull-up. + +Switching the default GPIO pull to "up" results in an input voltage +level of about 3.3V and ensures that an idle state (high signal) will +be detected if no IR receiver is attached. + +Signed-off-by: Matthias Reichl <hias@horus.com> +--- + arch/arm/boot/dts/overlays/README | 2 +- + arch/arm/boot/dts/overlays/gpio-ir-overlay.dts | 2 +- + 2 files changed, 2 insertions(+), 2 deletions(-) + +--- a/arch/arm/boot/dts/overlays/README ++++ b/arch/arm/boot/dts/overlays/README +@@ -611,7 +611,7 @@ Load: dtoverlay=gpio-ir,<param>=<val> + Params: gpio_pin Input pin number. Default is 18. + + gpio_pull Desired pull-up/down state (off, down, up) +- Default is "down". ++ Default is "up". + + rc-map-name Default rc keymap (can also be changed by + ir-keytable), defaults to "rc-rc6-mce" +--- a/arch/arm/boot/dts/overlays/gpio-ir-overlay.dts ++++ b/arch/arm/boot/dts/overlays/gpio-ir-overlay.dts +@@ -30,7 +30,7 @@ + gpio_ir_pins: gpio_ir_pins@12 { + brcm,pins = <18>; // pin 18 + brcm,function = <0>; // in +- brcm,pull = <1>; // down ++ brcm,pull = <2>; // up + }; + }; + }; |