Meizu M3: implement logarithmic brightness curve (curve provided by markun) and increase PWM frequency for the backlight.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21532 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 7 insertions, 5 deletions

diff --git a/firmware/export/config-meizu-m3.h b/firmware/export/config-meizu-m3.h
index 9e2d6cbf4e..06a0992550 100644
--- a/firmware/export/config-meizu-m3.h
+++ b/firmware/export/config-meizu-m3.h
@@ -179,6 +179,6 @@
 
 /* Main LCD backlight brightness range and defaults */
 #define MIN_BRIGHTNESS_SETTING      0
-#define MAX_BRIGHTNESS_SETTING      255
-#define DEFAULT_BRIGHTNESS_SETTING  200
+#define MAX_BRIGHTNESS_SETTING      15
+#define DEFAULT_BRIGHTNESS_SETTING  10
 
diff --git a/firmware/target/arm/s5l8700/backlight-meizu.c b/firmware/target/arm/s5l8700/backlight-meizu.c
index 43cbb16a2d..23dcbb1820 100644
--- a/firmware/target/arm/s5l8700/backlight-meizu.c
+++ b/firmware/target/arm/s5l8700/backlight-meizu.c
@@ -58,6 +58,8 @@ void INT_TIMERA(void)
 
 void _backlight_set_brightness(int brightness)
 {
+    static const unsigned char logtable[] = {0, 1, 2, 3, 5, 7, 10, 15, 22, 31, 44, 63, 90, 127, 180, 255};
+
     if (brightness == MIN_BRIGHTNESS_SETTING) {
         /* turn backlight fully off and disable interrupt */
         PDAT0 &= ~(1 << 2);
@@ -70,7 +72,7 @@ void _backlight_set_brightness(int brightness)
     }
     else {
         /* set PWM width and enable interrupt */
-        TADATA0 = brightness;
+        TADATA0 = logtable[brightness];
         INTMSK |= (1 << 5);
     }
 }
@@ -101,8 +103,8 @@ bool _backlight_init(void)
             (1 << 11) | /* TA_START */
             (3 << 8) |  /* TA_CS = PCLK / 64 */
             (1 << 4);   /* TA_MODE_SEL = PWM mode */
-    TADATA1 = MAX_BRIGHTNESS_SETTING;   /* set PWM period */
-    TAPRE = 100;    /* prescaler */
+    TADATA1 = 255;   /* set PWM period */
+    TAPRE = 30;    /* prescaler */
    
     _backlight_on();