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6025530738
The LP8556 datasheet describes an EN/VDDIO input, which serves "both as a chip enable and as a power supply reference for PWM, SDA, and SCL inputs." The LP8556 that I'm testing doesn't respond properly if I try to talk I2C to it too quickly after enabling VDDIO, and the LP8555 datasheet mentions a t_RESPONSE delay of up to 1 millisecond. Support this EN/VDDIO by adding a regulator property to the binding; enabling this regulator at probe time; and sleeping for 1 to 2ms, if the EN/VDDIO regulator was provided. Signed-off-by: Brian Norris <briannorris@chromium.org> Acked-by: Rob Herring <robh@kernel.org> Acked-by: Milo Kim <milo.kim@ti.com> Reviewed-by: Stephen Barber <smbarber@chromium.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
73 lines
1.7 KiB
Plaintext
73 lines
1.7 KiB
Plaintext
lp855x bindings
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Required properties:
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- compatible: "ti,lp8550", "ti,lp8551", "ti,lp8552", "ti,lp8553",
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"ti,lp8555", "ti,lp8556", "ti,lp8557"
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- reg: I2C slave address (u8)
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- dev-ctrl: Value of DEVICE CONTROL register (u8). It depends on the device.
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Optional properties:
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- bl-name: Backlight device name (string)
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- init-brt: Initial value of backlight brightness (u8)
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- pwm-period: PWM period value. Set only PWM input mode used (u32)
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- rom-addr: Register address of ROM area to be updated (u8)
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- rom-val: Register value to be updated (u8)
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- power-supply: Regulator which controls the 3V rail
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- enable-supply: Regulator which controls the EN/VDDIO input
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Example:
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/* LP8555 */
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backlight@2c {
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compatible = "ti,lp8555";
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reg = <0x2c>;
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dev-ctrl = /bits/ 8 <0x00>;
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pwm-period = <10000>;
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/* 4V OV, 4 output LED0 string enabled */
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rom_14h {
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rom-addr = /bits/ 8 <0x14>;
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rom-val = /bits/ 8 <0xcf>;
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};
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/* Heavy smoothing, 24ms ramp time step */
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rom_15h {
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rom-addr = /bits/ 8 <0x15>;
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rom-val = /bits/ 8 <0xc7>;
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};
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/* 4 output LED1 string enabled */
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rom_19h {
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rom-addr = /bits/ 8 <0x19>;
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rom-val = /bits/ 8 <0x0f>;
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};
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};
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/* LP8556 */
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backlight@2c {
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compatible = "ti,lp8556";
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reg = <0x2c>;
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bl-name = "lcd-bl";
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dev-ctrl = /bits/ 8 <0x85>;
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init-brt = /bits/ 8 <0x10>;
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};
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/* LP8557 */
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backlight@2c {
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compatible = "ti,lp8557";
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reg = <0x2c>;
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enable-supply = <&backlight_vddio>;
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power-supply = <&backlight_vdd>;
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dev-ctrl = /bits/ 8 <0x41>;
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init-brt = /bits/ 8 <0x0a>;
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/* 4V OV, 4 output LED string enabled */
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rom_14h {
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rom-addr = /bits/ 8 <0x14>;
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rom-val = /bits/ 8 <0xcf>;
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};
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};
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