Fuze PLUS Fix lcd_update_rect()

Lcd_update rect was hanging during horizontal screen update x = 238 and width = 2
which was within the bounds of the screen, this seems to be a weird corner case
but more testing needs done.

Update_rect now properly bounded between 0 - screen w/h
--Cleaned up code

Pixels in x are now multiples of 4.

Datasheet states:
-------------------------------------------------------------------------------------------
WORD_LENGTH=0 implies the input frame buffer is RGB 16 bits per pixel.
DATA_FORMAT_16_BIT field indicates if the pixels are in RGB 555 or RGB 565 format.
Limitations:
— BYTE_PACKING_FORMAT [3:0] should be 0x3 or 0xC if there is only one pixel per word.
— If there are two pixels per word, BYTE_PACKING_FORMAT [3:0] should be 0xF and
H_COUNT will be restricted to be a multiple of 2 pixels.

and

WORD_LENGTH=3 indicates that the input frame-buffer is RGB 24 bits per pixel (RGB 888). If
BYTE_PACKING_FORMAT [3:0] is 0x7, it indicates that there is only one pixel per 32-bit word
and there is no restriction on H_COUNT.
Limitations:
— If BYTE_PACKING_FORMAT [3:0] is 0xF, it indicates that the pixels are packed, i.e. there
are 4 pixels in 3 words or 12 bytes. In that case, H_COUNT must be a multiple of 4 pixels.
-------------------------------------------------------------------------------------------

We are using 16 bits per pixel and byte_packing = 0xF but device crashes with multiple of 2 pixels

Behaviour can be verified with plugin - oscilloscope, Horizontal mode device hangs as indicator
reaches right of screen

Change-Id: I1445f5334f4e7fe59304c65c76b47d0daa0614b2

1 files changed, 21 insertions, 6 deletions

diff --git a/firmware/target/arm/imx233/sansa-fuzeplus/lcd-fuzeplus.c b/firmware/target/arm/imx233/sansa-fuzeplus/lcd-fuzeplus.c
index d8ad5a8df3..224ff3d0fc 100644
--- a/firmware/target/arm/imx233/sansa-fuzeplus/lcd-fuzeplus.c
+++ b/firmware/target/arm/imx233/sansa-fuzeplus/lcd-fuzeplus.c
@@ -566,11 +566,26 @@ void lcd_update_rect(int x, int y, int w, int h)
     if(!lcd_on)
         return;
     #endif
-    /* make sure the rectangle is included in the screen */
-    x = MIN(x, LCD_WIDTH);
-    y = MIN(y, LCD_HEIGHT);
-    w = MIN(w, LCD_WIDTH - x);
-    h = MIN(h, LCD_HEIGHT - y);
+    /* make sure the rectangle is bounded in the screen */
+    if (w > LCD_WIDTH - x)/* Clip right */
+        w = LCD_WIDTH - x;
+    if (x < 0)/* Clip left */
+    {
+        w += x;
+        x = 0;
+    }
+    if (w <= 0)
+        return; /* nothing left to do */
+
+    if (h > LCD_HEIGHT - y) /* Clip bottom */
+        h = LCD_HEIGHT - y;
+    if (y < 0) /* Clip top */
+    {
+        h += y;
+        y = 0;
+    }
+    if (h <= 0)
+        return; /* nothing left to do */
 
     imx233_lcdif_wait_ready();
     lcd_write_reg(0x50, x);
@@ -612,7 +627,7 @@ void lcd_update_rect(int x, int y, int w, int h)
      * of w or h is odd, we will send a copy of the first pixels as dummy writes. We will
      * send at most 3 bytes. We then send (w * h + 3) / 4 x 4 bytes.
      */
-    if(w % 2 == 1 || h % 2 == 1)
+    if(w % 4 || (h & 1) == 1)
     {
         /* copy three pixel after the last one */
         for(int i = 0; i < 3; i++)