drivers/video/am335x-fb: Add support for 16bpp format

To support 16bpp we just need to change the raster_ctrl register
accordingly. Also 32bpp mode should work as well, but was not tested.
According to the TRM the uppermost byte will be ignored when
LCD_TFT_24BPP_UNPACK is set.

The switch logic is based on the Linux kernel tilcdc driver:
drivers/gpu/drm/tilcdc/tilcdc_crtc.c: lines 407 through 419
(kernel was checked out at commit: bcc981e9ed8)

Signed-off-by: Martin Pietryka <martin.pietryka@chello.at>
Reviewed-by: Hannes Schmelzer <oe5hpm@oevsv.at>
Tested-by: Hannes Schmelzer <oe5hpm@oevsv.at>

diff --git a/drivers/video/am335x-fb.c b/drivers/video/am335x-fb.c
index 0ec843f6b3a05cbd78599f9dcfe47ff0afa9e6fe..d984435ea48b5f6c25e9c4980ae8a6a178aa74a0 100644 (file)
--- a/drivers/video/am335x-fb.c
+++ b/drivers/video/am335x-fb.c
@@ -5,7 +5,7 @@
  * minimal framebuffer driver for TI's AM335x SoC to be compatible with
  * Wolfgang Denk's LCD-Framework (CONFIG_LCD, common/lcd.c)
  *
- * - supporting only 24bit RGB/TFT raster Mode (not using palette)
+ * - supporting 16/24/32bit RGB/TFT raster Mode (not using palette)
  * - sets up LCD controller as in 'am335x_lcdpanel' struct given
  * - starts output DMA from gd->fb_base buffer
  *
@@ -106,6 +106,8 @@ int lcd_get_size(int *line_length)
 
 int am335xfb_init(struct am335x_lcdpanel *panel)
 {
+       u32 raster_ctrl = 0;
+
        if (0 == gd->fb_base) {
                printf("ERROR: no valid fb_base stored in GLOBAL_DATA_PTR!\n");
                return -1;
@@ -115,6 +117,21 @@ int am335xfb_init(struct am335x_lcdpanel *panel)
                return -1;
        }
 
+       /* We can already set the bits for the raster_ctrl in this check */
+       switch (panel->bpp) {
+       case 16:
+               break;
+       case 32:
+               raster_ctrl |= LCD_TFT_24BPP_UNPACK;
+               /* fallthrough */
+       case 24:
+               raster_ctrl |= LCD_TFT_24BPP_MODE;
+               break;
+       default:
+               error("am335x-fb: invalid bpp value: %d\n", panel->bpp);
+               return -1;
+       }
+
        debug("setting up LCD-Controller for %dx%dx%d (hfp=%d,hbp=%d,hsw=%d / ",
              panel->hactive, panel->vactive, panel->bpp,
              panel->hfp, panel->hbp, panel->hsw);
@@ -157,8 +174,7 @@ int am335xfb_init(struct am335x_lcdpanel *panel)
                                LCD_HBPMSB(panel->hbp) |
                                LCD_HFPMSB(panel->hfp) |
                                0x0000FF00;     /* clk cycles for ac-bias */
-       lcdhw->raster_ctrl =    LCD_TFT_24BPP_MODE |
-                               LCD_TFT_24BPP_UNPACK |
+       lcdhw->raster_ctrl =    raster_ctrl |
                                LCD_PALMODE_RAWDATA |
                                LCD_TFT_MODE |
                                LCD_RASTER_ENABLE;