imx233: enable underflow recovery in lcdif (needed for freq scale)

When chaging the cpu and memory frequency we need to disable the
external memory interface (EMI) for a small time. This can
underflow the dma and cause some breakage. Hopefully the SSP
controller handles this gracefully by stopping the clock and the
I2C probably handles this naturally because the clock can be
streched anyway. However the LCDIF has a special setting for this
which needs to be enable, otherwise it will send garbage to the
LCD. No other block is known to suffer from this currently but
this issue might have more unexpected consequences.

Change-Id: Ide154cad87929f2bf6cc419ac1d2ff33e30eec66

5 files changed, 13 insertions, 0 deletions

diff --git a/firmware/target/arm/imx233/creative-zenxfi2/lcd-zenxfi2.c b/firmware/target/arm/imx233/creative-zenxfi2/lcd-zenxfi2.c
index 370104c724..f452ae083e 100644
--- a/firmware/target/arm/imx233/creative-zenxfi2/lcd-zenxfi2.c
+++ b/firmware/target/arm/imx233/creative-zenxfi2/lcd-zenxfi2.c
@@ -40,6 +40,7 @@ static void setup_parameters(void)
     imx233_lcdif_set_lcd_databus_width(HW_LCDIF_CTRL__LCD_DATABUS_WIDTH_18_BIT);
     imx233_lcdif_set_word_length(HW_LCDIF_CTRL__WORD_LENGTH_18_BIT);
     imx233_lcdif_set_timings(2, 2, 3, 3);
+    imx233_lcdif_enable_underflow_recover(true);
 }
 
 static void setup_lcd_pins(bool use_lcdif)
diff --git a/firmware/target/arm/imx233/creative-zenxfi3/lcd-zenxfi3.c b/firmware/target/arm/imx233/creative-zenxfi3/lcd-zenxfi3.c
index ea1ed6bccc..d04271369c 100644
--- a/firmware/target/arm/imx233/creative-zenxfi3/lcd-zenxfi3.c
+++ b/firmware/target/arm/imx233/creative-zenxfi3/lcd-zenxfi3.c
@@ -40,6 +40,7 @@ static void setup_parameters(void)
     imx233_lcdif_set_lcd_databus_width(HW_LCDIF_CTRL__LCD_DATABUS_WIDTH_16_BIT);
     imx233_lcdif_set_word_length(HW_LCDIF_CTRL__WORD_LENGTH_16_BIT);
     imx233_lcdif_set_timings(2, 2, 3, 3);
+    imx233_lcdif_enable_underflow_recover(true);
 }
 
 static void setup_lcd_pins(bool use_lcdif)
diff --git a/firmware/target/arm/imx233/lcdif-imx233.c b/firmware/target/arm/imx233/lcdif-imx233.c
index 285c2801ad..ad0931de40 100644
--- a/firmware/target/arm/imx233/lcdif-imx233.c
+++ b/firmware/target/arm/imx233/lcdif-imx233.c
@@ -23,6 +23,14 @@
 static unsigned lcdif_word_length = 0;
 static unsigned lcdif_byte_packing = 0;
 
+void imx233_lcdif_enable_underflow_recover(bool enable)
+{
+    if(enable)
+        __REG_SET(HW_LCDIF_CTRL1) = HW_LCDIF_CTRL1__RECOVER_ON_UNDERFLOW;
+    else
+        __REG_CLR(HW_LCDIF_CTRL1) = HW_LCDIF_CTRL1__RECOVER_ON_UNDERFLOW;
+}
+
 void imx233_lcdif_enable_bus_master(bool enable)
 {
     if(enable)
diff --git a/firmware/target/arm/imx233/lcdif-imx233.h b/firmware/target/arm/imx233/lcdif-imx233.h
index 3bce004259..9902aaa80b 100644
--- a/firmware/target/arm/imx233/lcdif-imx233.h
+++ b/firmware/target/arm/imx233/lcdif-imx233.h
@@ -53,6 +53,7 @@
 #define HW_LCDIF_CTRL1__IRQ_BP          8
 #define HW_LCDIF_CTRL1__BYTE_PACKING_FORMAT_BM  (0xf << 16)
 #define HW_LCDIF_CTRL1__BYTE_PACKING_FORMAT_BP  16
+#define HW_LCDIF_CTRL1__RECOVER_ON_UNDERFLOW    (1 << 24)
 
 #define HW_LCDIF__VSYNC_EDGE_IRQ        1
 #define HW_LCDIF__CUR_FRAME_DONE_IRQ    2
@@ -84,6 +85,7 @@
 #define HW_LCDIF_STAT__TXFIFO_EMPTY (1 << 26)
 #define HW_LCDIF_STAT__BUSY         (1 << 25)
 
+void imx233_lcdif_enable_underflow_recover(bool enable);
 void imx233_lcdif_enable_bus_master(bool enable);
 void imx233_lcdif_enable(bool enable);
 void imx233_lcdif_reset(void);// reset lcdif block
diff --git a/firmware/target/arm/imx233/sansa-fuzeplus/lcd-fuzeplus.c b/firmware/target/arm/imx233/sansa-fuzeplus/lcd-fuzeplus.c
index 34afc0478e..5f54c72b5e 100644
--- a/firmware/target/arm/imx233/sansa-fuzeplus/lcd-fuzeplus.c
+++ b/firmware/target/arm/imx233/sansa-fuzeplus/lcd-fuzeplus.c
@@ -54,6 +54,7 @@ static void setup_parameters(void)
     imx233_lcdif_set_lcd_databus_width(HW_LCDIF_CTRL__LCD_DATABUS_WIDTH_18_BIT);
     imx233_lcdif_set_word_length(HW_LCDIF_CTRL__WORD_LENGTH_18_BIT);
     imx233_lcdif_set_timings(1, 2, 2, 2);
+    imx233_lcdif_enable_underflow_recover(true);
 }
 
 static void setup_lcd_pins(bool use_lcdif)