video:da8xx-fb: Disable and reset sequence on version2 of LCDC

Patch follows the disable and software reset sequence specified
in version2 to LCDC functional specification.
Without this flicker is observed on re-enabling the LCDC.

Signed-off-by: Manjunathappa, Prakash <prakash.pm@ti.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/video/da8xx-fb.c b/drivers/video/da8xx-fb.c
index 55f91d9ab00b..29577bf1f559 100644
--- a/drivers/video/da8xx-fb.c
+++ b/drivers/video/da8xx-fb.c
@@ -116,6 +116,7 @@
 /* Clock registers available only on Version 2 */
 #define  LCD_CLK_ENABLE_REG                     0x6c
 #define  LCD_CLK_RESET_REG                      0x70
+#define  LCD_CLK_MAIN_RESET                     BIT(3)
 
 #define LCD_NUM_BUFFERS 2
 
@@ -244,6 +245,10 @@ static inline void lcd_enable_raster(void)
 {
         u32 reg;
 
+        /* Bring LCDC out of reset */
+        if (lcd_revision == LCD_VERSION_2)
+                lcdc_write(0, LCD_CLK_RESET_REG);
+
         reg = lcdc_read(LCD_RASTER_CTRL_REG);
         if (!(reg & LCD_RASTER_ENABLE))
                 lcdc_write(reg | LCD_RASTER_ENABLE, LCD_RASTER_CTRL_REG);
@@ -257,6 +262,10 @@ static inline void lcd_disable_raster(void)
         reg = lcdc_read(LCD_RASTER_CTRL_REG);
         if (reg & LCD_RASTER_ENABLE)
                 lcdc_write(reg & ~LCD_RASTER_ENABLE, LCD_RASTER_CTRL_REG);
+
+        if (lcd_revision == LCD_VERSION_2)
+                /* Write 1 to reset LCDC */
+                lcdc_write(LCD_CLK_MAIN_RESET, LCD_CLK_RESET_REG);
 }
 
 static void lcd_blit(int load_mode, struct da8xx_fb_par *par)
@@ -584,8 +593,12 @@ static void lcd_reset(struct da8xx_fb_par *par)
         lcdc_write(0, LCD_DMA_CTRL_REG);
         lcdc_write(0, LCD_RASTER_CTRL_REG);
 
-        if (lcd_revision == LCD_VERSION_2)
+        if (lcd_revision == LCD_VERSION_2) {
                 lcdc_write(0, LCD_INT_ENABLE_SET_REG);
+                /* Write 1 to reset */
+                lcdc_write(LCD_CLK_MAIN_RESET, LCD_CLK_RESET_REG);
+                lcdc_write(0, LCD_CLK_RESET_REG);
+        }
 }
 
 static void lcd_calc_clk_divider(struct da8xx_fb_par *par)