configs: Review all implementations of board_lcd_initialize(). The NuttX convention is that all internal functions that return errors as an 'int' must return a negated errno value on failure and a non-negative value on success. Most were right but eight of them had cloned logic that returns 1 on success and zero on failure... both of which are interpreted as success by the caller since they are non-negative.

configs/hymini-stm32v/src/stm32_r61505u.c

@@ -1,7 +1,7 @@
 /************************************************************************************
  * configs/hymini-stm32v/src/stm32_r61505u.c
  *
- *   Copyright (C) 2009, 2011, 2013 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2009, 2011, 2013, 2018 Gregory Nutt. All rights reserved.
  *   Authors: Gregory Nutt <gnutt@nuttx.org>
  *            Laurent Latil <laurent@latil.nom.fr>
  *            C. Faure 2013-05-15
@@ -924,13 +924,13 @@ int board_lcd_initialize(void)
 
   /* Check model id */
 
-  id=read_reg(0x0);
+  id = read_reg(0x0);
   if (id != LCD_ID)
     {
       /* Not a R61505U ? */
 
       lcderr("ERROR: board_lcd_initialize: LCD ctrl is not a R61505U");
-      return ERROR;
+      return -ENXIO;
     }
 
   /* Configure and enable LCD */

configs/mikroe-stm32f4/src/stm32_appinit.c

@@ -376,11 +376,10 @@ int board_app_initialize(uintptr_t arg)
   syslog(LOG_INFO, "Initializing TFT LCD module\n");
 
   ret = board_lcd_initialize();
-  if (ret != OK)
+  if (ret < 0)
     {
       syslog(LOG_ERR, "ERROR: Failed to initialize TFT LCD module\n");
     }
-
 #endif
 
 #ifdef CONFIG_SENSORS_QENCODER

configs/stm32f103-minimum/src/stm32_lcd.c

@@ -103,13 +103,13 @@ int board_lcd_initialize(void)
   if (!g_spidev)
     {
       lcderr("ERROR: Failed to initialize SPI port %d\n", LCD_SPI_PORTNO);
-      return 0;
+      return -ENODEV;
     }
 
   stm32_gpiowrite(STM32_LCD_RST, 0);
   up_mdelay(1);
   stm32_gpiowrite(STM32_LCD_RST, 1);
-  return 1;
+  return OK;
 }
 
 /****************************************************************************

configs/stm32f103-minimum/src/stm32_max7219.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * config/stm32f103-minimum/src/stm32_max7219.c
  *
- *   Copyright (C) 2017 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2017-2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -88,10 +88,10 @@ int board_lcd_initialize(void)
   if (!g_spidev)
     {
       lcderr("ERROR: Failed to initialize SPI port %d\n", LCD_SPI_PORTNO);
-      return 0;
+      return -ENODEV;
     }
 
-  return 1;
+  return OK;
 }
 
 /****************************************************************************

configs/stm32f103-minimum/src/stm32_pcd8544.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * config/stm32f103-minimum/src/stm32_pcd8544.c
  *
- *   Copyright (C) 2011, 2013, 2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2011, 2013, 2015, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -95,13 +95,13 @@ int board_lcd_initialize(void)
   if (!g_spidev)
     {
       lcderr("ERROR: Failed to initialize SPI port %d\n", LCD_SPI_PORTNO);
-      return 0;
+      return -ENODEV;
     }
 
   stm32_gpiowrite(STM32_LCD_RST, 0);
   up_mdelay(10);
   stm32_gpiowrite(STM32_LCD_RST, 1);
-  return 1;
+  return OK;
 }
 
 /****************************************************************************

configs/stm32f103-minimum/src/stm32_ssd1306.c

@@ -88,10 +88,10 @@ int board_lcd_initialize(void)
   if (!g_i2c)
     {
       lcderr("ERROR: Failed to initialize I2C port %d\n", OLED_I2C_PORT);
-      return 0;
+      return -ENODEV;
     }
 
-  return 1;
+  return OK;
 }
 
 /****************************************************************************

configs/stm32f4discovery/src/stm32_st7567.c

@@ -103,13 +103,13 @@ int board_lcd_initialize(void)
   if (!g_spidev)
     {
       lcderr("ERROR: Failed to initialize SPI port %d\n", LCD_SPI_PORTNO);
-      return 0;
+      return -ENODEV;
     }
 
   stm32_gpiowrite(STM32_LCD_RST, 0);
   up_mdelay(1);
   stm32_gpiowrite(STM32_LCD_RST, 1);
-  return 1;
+  return OK;
 }
 
 /****************************************************************************

configs/zkit-arm-1769/src/lpc17_lcd.c

@@ -6,7 +6,7 @@
  *
  * Based on configs/lm3s6965-ek/src/up_oled.c
  *
- *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2012, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -91,13 +91,13 @@ int board_lcd_initialize(void)
   if (!g_spidev)
     {
       lcderr("ERROR: Failed to initialize SSP port 0\n");
-      return 0;
+      return -ENODEV;
     }
 
   lpc17_gpiowrite(ZKITARM_OLED_RST, 0);
   up_mdelay(1);
   lpc17_gpiowrite(ZKITARM_OLED_RST, 1);
-  return 1;
+  return OK;
 }
 
 /****************************************************************************