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ar71xx: fix Arduino Yun enabling of level shifters outputs

As show in Arduino Yun schematic [1] GPIO 21 and 22 are connected to
output enable pin (OE) of two NTB01xx level shifters.

NTB01xx datasheets [2] [3] states that OE pin are active-high
therefore we should initialize GPIO 21 (DS_GPIO_OE) and GPIO 22
(DS_GPIO_OE2) accordingly to actually enable level shifters outputs.

[1] https://www.arduino.cc/en/uploads/Main/arduino-Yun-schematic.pdf
[2] https://www.nxp.com/docs/en/data-sheet/NTB0102.pdf
[3] https://www.nxp.com/docs/en/data-sheet/NTB0104.pdf

Signed-off-by: Edoardo Scaglia <edoardo.87@gmail.com>
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escaglia authored and xback committed Feb 1, 2019
1 parent 07e6ce4 commit 077253dd666a30ae5231c3748222d4b5b138593d
Showing with 2 additions and 2 deletions.
  1. +2 −2 target/linux/ar71xx/files/arch/mips/ath79/mach-arduino-yun.c
@@ -141,7 +141,7 @@ static void __init ds_setup(void)

// enable OE of level shifter
if (gpio_request_one(DS_GPIO_OE,
GPIOF_OUT_INIT_LOW | GPIOF_EXPORT_DIR_FIXED, "OE-1") != 0)
GPIOF_OUT_INIT_HIGH | GPIOF_EXPORT_DIR_FIXED, "OE-1") != 0)
printk("Error setting GPIO OE\n");

if (gpio_request_one(DS_GPIO_UART_ENA,
@@ -150,7 +150,7 @@ static void __init ds_setup(void)

// enable OE of level shifter
if (gpio_request_one(DS_GPIO_OE2,
GPIOF_OUT_INIT_LOW | GPIOF_EXPORT_DIR_FIXED, "OE-2") != 0)
GPIOF_OUT_INIT_HIGH | GPIOF_EXPORT_DIR_FIXED, "OE-2") != 0)
printk("Error setting GPIO OE2\n");
}

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