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Phil Elwellpopcornmix
Phil Elwell
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BCM270X_DT: Add pwm and pwm-2chan overlays
From the README entries: Legal pin,function combinations for each channel: PWM0: 12,4(Alt0) 18,2(Alt5) 40,4(Alt0) 52,5(Alt1) PWM1: 13,4(Alt0) 19,2(Alt5) 41,4(Alt0) 45,4(Alt0) 53,5(Alt1) N.B.: 1) Pin 18 is the only one available on all platforms, and it is the one used by the I2S audio interface. Pins 12 and 13 might be better choices on an A+, B+ or Pi2. 2) The onboard analogue audio output uses both PWM channels. 3) So be careful mixing audio and PWM. 4) Currently the clock must have been enabled and configured by other means. See: #756
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‎arch/arm/boot/dts/bcm2708_common.dtsi

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@@ -154,6 +154,14 @@
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status = "disabled";
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};
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pwm: pwm@7e20c000 {
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compatible = "brcm,bcm2835-pwm";
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reg = <0x7e20c000 0x28>;
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clocks = <&clk_pwm>;
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#pwm-cells = <2>;
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status = "disabled";
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};
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uart1: uart@7e215040 {
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compatible = "brcm,bcm2835-aux-uart", "ns16550";
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reg = <0x7e215040 0x40>;
@@ -279,6 +287,14 @@
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clock-output-names = "apb_pclk";
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clock-frequency = <126000000>;
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};
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clk_pwm: clock@5 {
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compatible = "fixed-clock";
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reg = <3>;
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#clock-cells = <0>;
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clock-output-names = "pwm";
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clock-frequency = <100000000>;
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};
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};
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__overrides__ {

‎arch/arm/boot/dts/overlays/Makefile

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@@ -35,6 +35,8 @@ dtb-$(RPI_DT_OVERLAYS) += mz61581-overlay.dtb
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dtb-$(RPI_DT_OVERLAYS) += piscreen-overlay.dtb
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dtb-$(RPI_DT_OVERLAYS) += pitft28-resistive-overlay.dtb
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dtb-$(RPI_DT_OVERLAYS) += pps-gpio-overlay.dtb
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dtb-$(RPI_DT_OVERLAYS) += pwm-overlay.dtb
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dtb-$(RPI_DT_OVERLAYS) += pwm-2chan-overlay.dtb
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dtb-$(RPI_DT_OVERLAYS) += rpi-dac-overlay.dtb
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dtb-$(RPI_DT_OVERLAYS) += rpi-display-overlay.dtb
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dtb-$(RPI_DT_OVERLAYS) += rpi-ft5406-overlay.dtb

‎arch/arm/boot/dts/overlays/README

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@@ -410,6 +410,47 @@ Load: dtoverlay=pps-gpio,<param>=<val>
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Params: gpiopin Input GPIO (default "18")
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Name: pwm
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Info: Configures a single PWM channel
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Legal pin,function combinations for each channel:
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PWM0: 12,4(Alt0) 18,2(Alt5) 40,4(Alt0) 52,5(Alt1)
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PWM1: 13,4(Alt0) 19,2(Alt5) 41,4(Alt0) 45,4(Alt0) 53,5(Alt1)
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N.B.:
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1) Pin 18 is the only one available on all platforms, and
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it is the one used by the I2S audio interface.
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Pins 12 and 13 might be better choices on an A+, B+ or Pi2.
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2) The onboard analogue audio output uses both PWM channels.
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3) So be careful mixing audio and PWM.
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4) Currently the clock must have been enabled and configured
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by other means.
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Load: dtoverlay=pwm-2chan,<param>=<val>
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Load: dtoverlay=pwm,<param>=<val>
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Params: pin Output pin (default 18) - see table
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func Pin function (default 2 = Alt5) - see above
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clock PWM clock frequency (informational)
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Name: pwm-2chan
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Info: Configures both PWM channels
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Legal pin,function combinations for each channel:
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PWM0: 12,4(Alt0) 18,2(Alt5) 40,4(Alt0) 52,5(Alt1)
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PWM1: 13,4(Alt0) 19,2(Alt5) 41,4(Alt0) 45,4(Alt0) 53,5(Alt1)
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N.B.:
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1) Pin 18 is the only one available on all platforms, and
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it is the one used by the I2S audio interface.
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Pins 12 and 13 might be better choices on an A+, B+ or Pi2.
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2) The onboard analogue audio output uses both PWM channels.
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3) So be careful mixing audio and PWM.
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4) Currently the clock must have been enabled and configured
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by other means.
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Load: dtoverlay=pwm-2chan,<param>=<val>
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Params: pin Output pin (default 18) - see table
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pin2 Output pin for other channel (default 19)
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func Pin function (default 2 = Alt5) - see above
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func2 Function for pin2 (default 2 = Alt5)
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clock PWM clock frequency (informational)
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Name: rpi-dac
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Info: Configures the RPi DAC audio card
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Load: dtoverlay=rpi-dac

‎arch/arm/boot/dts/overlays/pwm-2chan-overlay.dts

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/dts-v1/;
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/plugin/;
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/*
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This is the 2-channel overlay - only use it if you need both channels.
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Legal pin,function combinations for each channel:
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PWM0: 12,4(Alt0) 18,2(Alt5) 40,4(Alt0) 52,5(Alt1)
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PWM1: 13,4(Alt0) 19,2(Alt5) 41,4(Alt0) 45,4(Alt0) 53,5(Alt1)
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N.B.:
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1) Pin 18 is the only one available on all platforms, and
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it is the one used by the I2S audio interface.
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Pins 12 and 13 might be better choices on an A+, B+ or Pi2.
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2) The onboard analogue audio output uses both PWM channels.
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3) So be careful mixing audio and PWM.
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*/
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/ {
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fragment@0 {
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target = <&gpio>;
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__overlay__ {
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pwm_pins: pwm_pins {
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brcm,pins = <18 19>;
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brcm,function = <2 2>; /* Alt5 */
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};
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};
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};
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fragment@1 {
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target = <&pwm>;
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__overlay__ {
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pinctrl-names = "default";
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pinctrl-0 = <&pwm_pins>;
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status = "okay";
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};
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};
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__overrides__ {
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pin = <&pwm_pins>,"brcm,pins:0";
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pin2 = <&pwm_pins>,"brcm,pins:4";
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func = <&pwm_pins>,"brcm,function:0";
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func2 = <&pwm_pins>,"brcm,function:4";
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clock = <&clk_pwm>,"clock-frequency:0";
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};
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};

‎arch/arm/boot/dts/overlays/pwm-overlay.dts

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/dts-v1/;
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/plugin/;
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/*
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Legal pin,function combinations for each channel:
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PWM0: 12,4(Alt0) 18,2(Alt5) 40,4(Alt0) 52,5(Alt1)
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PWM1: 13,4(Alt0) 19,2(Alt5) 41,4(Alt0) 45,4(Alt0) 53,5(Alt1)
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N.B.:
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1) Pin 18 is the only one available on all platforms, and
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it is the one used by the I2S audio interface.
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Pins 12 and 13 might be better choices on an A+, B+ or Pi2.
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2) The onboard analogue audio output uses both PWM channels.
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3) So be careful mixing audio and PWM.
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*/
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/ {
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fragment@0 {
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target = <&gpio>;
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__overlay__ {
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pwm_pins: pwm_pins {
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brcm,pins = <18>;
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brcm,function = <2>; /* Alt5 */
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};
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};
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};
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fragment@1 {
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target = <&pwm>;
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__overlay__ {
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pinctrl-names = "default";
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pinctrl-0 = <&pwm_pins>;
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status = "okay";
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};
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};
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__overrides__ {
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pin = <&pwm_pins>,"brcm,pins:0";
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func = <&pwm_pins>,"brcm,function:0";
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clock = <&clk_pwm>,"clock-frequency:0";
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};
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};

‎arch/arm/configs/bcm2709_defconfig

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@@ -1087,6 +1087,7 @@ CONFIG_IIO_BUFFER=y
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CONFIG_IIO_BUFFER_CB=y
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CONFIG_IIO_KFIFO_BUF=m
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CONFIG_DHT11=m
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CONFIG_PWM_BCM2835=m
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CONFIG_RASPBERRYPI_FIRMWARE=y
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CONFIG_EXT4_FS=y
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CONFIG_EXT4_FS_POSIX_ACL=y

‎arch/arm/configs/bcmrpi_defconfig

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@@ -1080,6 +1080,7 @@ CONFIG_IIO_BUFFER=y
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CONFIG_IIO_BUFFER_CB=y
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CONFIG_IIO_KFIFO_BUF=m
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CONFIG_DHT11=m
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CONFIG_PWM_BCM2835=m
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CONFIG_RASPBERRYPI_FIRMWARE=y
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CONFIG_EXT4_FS=y
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CONFIG_EXT4_FS_POSIX_ACL=y

‎drivers/pwm/Kconfig

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@@ -85,7 +85,7 @@ config PWM_BCM_KONA
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config PWM_BCM2835
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tristate "BCM2835 PWM support"
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depends on ARCH_BCM2835
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depends on ARCH_BCM2835 || ARCH_BCM2708 || ARCH_BCM2709
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help
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PWM framework driver for BCM2835 controller (Raspberry Pi)
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