From cad91ed938049037a57e9bcc4c5ad63e45dbc2e6 Mon Sep 17 00:00:00 2001
From: Marcin Bukat <marcin.bukat@gmail.com>
Date: Thu, 14 Jul 2011 17:06:44 +0000
Subject: rk27xx - fix backlight driver - now one can set brightness

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30138 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/target/arm/rk27xx/backlight-rk27xx.c | 32 ++++++++++++++++-----------
 1 file changed, 19 insertions(+), 13 deletions(-)

(limited to 'firmware/target/arm')

diff --git a/firmware/target/arm/rk27xx/backlight-rk27xx.c b/firmware/target/arm/rk27xx/backlight-rk27xx.c
index 0d871924ea..e759220dff 100644
--- a/firmware/target/arm/rk27xx/backlight-rk27xx.c
+++ b/firmware/target/arm/rk27xx/backlight-rk27xx.c
@@ -25,6 +25,14 @@
 #include "backlight-target.h"
 #include "system.h"
 
+static int brightness = DEFAULT_BRIGHTNESS_SETTING;
+static const unsigned short log_brightness[] = {
+    0x2710, 0x27ac, 0x2849, 0x2983, 0x2abd, 0x2c93, 0x2e6a, 0x30dd,
+    0x3351, 0x3661, 0x3971, 0x3d1f, 0x40cc, 0x4516, 0x4960, 0x4e47,
+    0x532e, 0x58b1, 0x5e35, 0x6456, 0x6a76, 0x7134, 0x77f1, 0x7f4c,
+    0x86a6, 0x8e9d, 0x9695, 0x9f29, 0xa7bd, 0xb0ee, 0xba1f, 0xc350
+};
+
 bool _backlight_init(void)
 {
     /* configure PD4 as output */
@@ -36,15 +44,18 @@ bool _backlight_init(void)
     /* IOMUXB - set PWM0 pin as GPIO */
     SCU_IOMUXB_CON &= ~(1 << 11); /* type<<11<<channel */
 
-    /* setup pwm */
+    /* DIV/2, PWM reset */
     PWMT0_CTRL = (0<<9) | (1<<7);
 
-    /* set pwm frequency ~10kHz */
-    /* (apb_freq/pwm_freq)/pwm_div = (50 000 000/10 000)/2 */
-    PWMT0_LRC = 2500; 
-    PWMT0_HRC = 1;
+    /* set pwm frequency to 500Hz - my lcd panel can't cope more reliably */
+    /* (apb_freq/pwm_freq)/pwm_div = (50 000 000/500)/2 */
+    PWMT0_LRC = 50000; 
+    PWMT0_HRC = log_brightness[brightness];
 
+    /* reset counter */
     PWMT0_CNTR = 0x00;
+    
+    /* DIV/2, PWM output enable, PWM timer enable */
     PWMT0_CTRL = (0<<9) | (1<<3) | (1<<0);
 
     return true;
@@ -58,11 +69,6 @@ void _backlight_on(void)
     /* set output pin as PWM pin */
     SCU_IOMUXB_CON |= (1<<11); /* type<<11<<channel */
 
-    /* 100% duty cycle. Other settings doesn't work for
-     * unknown reason
-     */
-    PWMT0_HRC = PWMT0_LRC;
-
     /* pwm enable */
     PWMT0_CTRL |= (1<<3) | (1<<0);
 }
@@ -79,8 +85,8 @@ void _backlight_off(void)
     SCU_CLKCFG |= (1<<29);
 }
 
-void _backlight_set_brightness(int brightness)
+void _backlight_set_brightness(int val)
 {
-    (void)brightness;
-    /* doesn't work for unknown reason */
+    brightness = val & 0x1f;
+    PWMT0_HRC = log_brightness[brightness];
 }
-- 
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