Properly implement backlighting on Onda VX7x7 (using PWM).

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21235 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 34 insertions, 72 deletions

diff --git a/firmware/export/config-ondavx747.h b/firmware/export/config-ondavx747.h
index d735c045e2..2e757f36be 100644
--- a/firmware/export/config-ondavx747.h
+++ b/firmware/export/config-ondavx747.h
@@ -102,17 +102,14 @@
 #define HAVE_BACKLIGHT
 #define HAVE_BACKLIGHT_BRIGHTNESS
 
-/* define this if the backlight can be set to a brightness */
-#define __BACKLIGHT_INIT
-
 /* Which backlight fading type? */
-//#define CONFIG_BACKLIGHT_FADING BACKLIGHT_FADING_PWM
+#define CONFIG_BACKLIGHT_FADING BACKLIGHT_FADING_SW_HW_REG
 
 /* Main LCD backlight brightness range and defaults */
-#define MIN_BRIGHTNESS_SETTING          100
-#define MAX_BRIGHTNESS_SETTING          300
-#define DEFAULT_BRIGHTNESS_SETTING      300 /* "full brightness" */
-#define DEFAULT_DIMNESS_SETTING         100 /* "most dim" */
+#define MIN_BRIGHTNESS_SETTING          1
+#define MAX_BRIGHTNESS_SETTING          30
+#define DEFAULT_BRIGHTNESS_SETTING      30 /* "full brightness" */
+#define DEFAULT_DIMNESS_SETTING         1 /* "most dim" */
 
 /* Define this if you have a software controlled poweroff */
 #define HAVE_SW_POWEROFF
diff --git a/firmware/target/mips/ingenic_jz47xx/onda_vx747/backlight-onda_vx7X7.c b/firmware/target/mips/ingenic_jz47xx/onda_vx747/backlight-onda_vx7X7.c
index 72e469977b..391af0acb7 100644
--- a/firmware/target/mips/ingenic_jz47xx/onda_vx747/backlight-onda_vx7X7.c
+++ b/firmware/target/mips/ingenic_jz47xx/onda_vx747/backlight-onda_vx7X7.c
@@ -27,84 +27,50 @@
 #define BACKLIGHT_GPIO  (32*3+31)
 #define BACKLIGHT_PWM   7
 
-/* TODO: use HW PWM */
-#define SW_PWM 1
-#if SW_PWM
-
-static bool backlight_on;
+/* PWM counter (PWM INITL = 0):
+ * [0, PWM half rate[ -> backlight off
+ * [PWM half rate, PWM full rate[ -> backlight on
+ * [PWM full rate, PWM full rate] -> counter reset to 0
+ */
+static int old_val;
 static void set_backlight(int val)
 {
-    (void)val;
-}
+    if(val == old_val)
+        return;
 
-bool _backlight_init(void)
-{
-    __gpio_as_output(BACKLIGHT_GPIO);
-    __gpio_set_pin(BACKLIGHT_GPIO);
-    
-    backlight_on = true;
+    /* The pulse repetition frequency should be greater than 100Hz so
+       the flickering is not perceptible to the human eye but
+       not greater than about 1kHz. */
 
-    return true;
-}
+    /* Clock = 8192 Hz */
+    /* 1 <= val <= 30 */
+    int cycle = (MAX_BRIGHTNESS_SETTING - val + 1);
 
-void _backlight_on(void)
-{
-    if(!backlight_on)
-        __gpio_set_pin(BACKLIGHT_GPIO);
-    
-    backlight_on = true;
-}
+    __tcu_disable_pwm_output(BACKLIGHT_PWM);
+    __tcu_stop_counter(BACKLIGHT_PWM);
 
-void _backlight_off(void)
-{
-    if(backlight_on)
-        __gpio_clear_pin(BACKLIGHT_GPIO);
-    
-    backlight_on = false;
-}
+    __tcu_set_count(BACKLIGHT_PWM, 0);
+    __tcu_set_half_data(BACKLIGHT_PWM, cycle-1);
+    __tcu_set_full_data(BACKLIGHT_PWM, cycle);
 
-#else
+    __tcu_start_counter(BACKLIGHT_PWM);
+    __tcu_enable_pwm_output(BACKLIGHT_PWM);
 
-static int old_val;
-static void set_backlight(int val)
-{
-    if(val == old_val)
-        return;
-    
-    /* Taken from the OF */
-    int tmp;
-    tmp = (val/2 + __cpm_get_rtcclk()) / val;
-    if(tmp > 0xFFFF)
-        tmp = 0xFFFF;
-
-    __tcu_set_half_data(BACKLIGHT_PWM, (tmp * val * 1374389535) >> 5);
-    __tcu_set_full_data(BACKLIGHT_PWM, tmp);
-    
     old_val = val;
 }
 
 static void set_backlight_on(void)
 {
-    if(old_val == MAX_BRIGHTNESS_SETTING)
-        return;
-    
-    __tcu_start_timer_clock(BACKLIGHT_PWM);
-    
-    set_backlight(MAX_BRIGHTNESS_SETTING);
-
-    __tcu_set_count(BACKLIGHT_PWM, 0);
-    __tcu_start_counter(BACKLIGHT_PWM);
+    set_backlight(old_val);
 
     __tcu_enable_pwm_output(BACKLIGHT_PWM);
+    __tcu_start_counter(BACKLIGHT_PWM);
 }
 
 static void set_backlight_off(void)
 {
     __tcu_stop_counter(BACKLIGHT_PWM);
     __tcu_disable_pwm_output(BACKLIGHT_PWM);
-    __tcu_stop_timer_clock(BACKLIGHT_PWM);
-    
-    old_val = -1;
 }
 
 bool _backlight_init(void)
@@ -113,17 +79,17 @@ bool _backlight_init(void)
     __tcu_start_timer_clock(BACKLIGHT_PWM);
 
     __tcu_stop_counter(BACKLIGHT_PWM);
-    __tcu_disable_pwm_output(BACKLIGHT_PWM);
-
     __tcu_init_pwm_output_low(BACKLIGHT_PWM);
-    __tcu_select_rtcclk(BACKLIGHT_PWM);
-    __tcu_select_clk_div1(BACKLIGHT_PWM);
+    __tcu_set_pwm_output_shutdown_graceful(BACKLIGHT_PWM);
+    __tcu_enable_pwm_output(BACKLIGHT_PWM);
+
+    __tcu_select_rtcclk(BACKLIGHT_PWM); /* 32.768 kHz */
+    __tcu_select_clk_div1(BACKLIGHT_PWM); /* 8.192 kHz */
 
     __tcu_mask_half_match_irq(BACKLIGHT_PWM);
     __tcu_mask_full_match_irq(BACKLIGHT_PWM);
-    
-    old_val = -1;
 
+    old_val = MAX_BRIGHTNESS_SETTING;
     set_backlight_on();
 
     return true;
@@ -138,7 +104,6 @@ void _backlight_off(void)
 {
     set_backlight_off();
 }
-#endif /* !SW_PWM */
 
 #ifdef HAVE_BACKLIGHT_BRIGHTNESS
 void _backlight_set_brightness(int brightness)