Merged in MarcoKrahl/nuttx/ltdc (pull request #654)

LTDC fixes

* stm32_ltdc: Allows to use ltdc without overlay support

    Signed-off-by: Marco Krahl <ocram.lhark@gmail.com>

* stm32: Removes overlay dependency when LTDC is enabled

    Signed-off-by: Marco Krahl <ocram.lhark@gmail.com>

* stm32: Allows to configure initial chromakey for LTDC layer

    Signed-off-by: Marco Krahl <ocram.lhark@gmail.com>

* stm32_ltdc: Fixes another compiler warning when dma2d is disabled

    Signed-off-by: Marco Krahl <ocram.lhark@gmail.com>

* stm32_ltdc: Checks for register reload is done before continued

    Signed-off-by: Marco Krahl <ocram.lhark@gmail.com>

* stm32f429i-disco: Fixes eliminated register control by compiler optimization

    When reading 1 byte from the SPI device the clock must be enabled and
    immediately disabled. This section has been optimized by the compiler (-O2) to a
    missing active spi clock. A subsequently block read failed because of missing
    response from the spi device. This has been lead to a broken display
    initializing.

    Signed-off-by: Marco Krahl <ocram.lhark@gmail.com>

Approved-by: Gregory Nutt <gnutt@nuttx.org>

arch/arm/src/stm32/Kconfig

@@ -2437,7 +2437,6 @@ config STM32_LTDC
 	bool "LTDC"
 	default n
 	select FB
-	select FB_OVERLAY
 	depends on STM32_HAVE_LTDC
 	---help---
 		The STM32 LTDC is an LCD-TFT Display Controller available on
@@ -8180,13 +8179,17 @@ config STM32_LTDC_FB_SIZE
     ---help---
         Must be the whole size of the active LTDC layer.
 
-config STM32_LTDC_L1_CHROMAKEY
+config STM32_LTDC_L1_CHROMAKEYEN
 	bool "Enable chromakey support for layer 1"
 	default y
 
+config STM32_LTDC_L1_CHROMAKEY
+	hex "Layer L1 initial chroma key"
+	default 0x00000000
+
 config STM32_LTDC_L1_COLOR
-    hex "Layer L1 default color"
-    default 0x00000000
+	hex "Layer L1 default color"
+	default 0x00000000
 
 choice
 	prompt "Layer 1 color format"
@@ -8236,10 +8239,14 @@ config STM32_LTDC_L2_COLOR
 	hex "Layer L2 default color"
 	default 0x00000000
 
-config STM32_LTDC_L2_CHROMAKEY
+config STM32_LTDC_L2_CHROMAKEYEN
 	bool "Enable chromakey support for layer 2"
 	default y
 
+config STM32_LTDC_L2_CHROMAKEY
+	hex "Layer L2 initial chroma key"
+	default 0x00000000
+
 choice
 	prompt "Layer 2 (top layer) color format"
 	default STM32_LTDC_L2_RGB565

configs/stm32f429i-disco/src/stm32_ili93414ws.c

@@ -513,9 +513,9 @@ static int stm32_ili93414ws_sendblock(FAR struct ili93414ws_lcd_s *lcd,
 
 static uint16_t stm32_ili93414ws_recvword(void)
 {
-  volatile uint8_t   n;
-          uint16_t   regval;
-        irqstate_t   flags;
+  volatile int       n;
+  volatile uint16_t  regval;
+         irqstate_t  flags;
 
   /* Disable interrupts during time critical spi sequence.
    * In bidrectional receive mode the data transfer can only be stopped by