[U-Boot] [PATCH v3 2/2] drivers/video/am335x-fb: Properly point framebuffer behind palette

Martin Pietryka
2016-04-27T19:39:16Z

The DMA was outputting the palette on the screen because the base
for the DMA was not after the palette. In addition to that, the ceiling was
also too high, this led that the output on the screen was shifted.

NOTE: According to the TRM, even in 16/24bit mode a palette is required
in the first 32 bytes of the framebuffer.

See also:
https://e2e.ti.com/support/arm/sitara_arm/f/791/p/234967/834483#834483

"In this mode, the LCDC will assume all information is data and thus you
need to ensure that the DMA points to the first pixel of data and not the
first entry in the frame buffer which is the beginning of the 512 byte
palette."

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

Changes in v3: None

drivers/video/am335x-fb.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/video/am335x-fb.c b/drivers/video/am335x-fb.c
index d984435..bb5cc97 100644
--- a/drivers/video/am335x-fb.c
+++ b/drivers/video/am335x-fb.c
@@ -143,6 +143,8 @@ int am335xfb_init(struct am335x_lcdpanel *panel)
/* palette default entry */
memset((void *)gd->fb_base, 0, 0x20);
*(unsigned int *)gd->fb_base = 0x4000;
+ /* point fb behind palette */
+ gd->fb_base += 0x20;

/* turn ON display through powercontrol function if accessible */
if (0 != panel->panel_power_ctrl)
@@ -154,9 +156,9 @@ int am335xfb_init(struct am335x_lcdpanel *panel)
lcdhw->raster_ctrl = 0;
lcdhw->ctrl = LCD_CLK_DIVISOR(panel->pxl_clk_div) | LCD_RASTER_MODE;
lcdhw->lcddma_fb0_base = gd->fb_base;
- lcdhw->lcddma_fb0_ceiling = gd->fb_base + FBSIZE(panel) + 0x20;
+ lcdhw->lcddma_fb0_ceiling = gd->fb_base + FBSIZE(panel);
lcdhw->lcddma_fb1_base = gd->fb_base;
- lcdhw->lcddma_fb1_ceiling = gd->fb_base + FBSIZE(panel) + 0x20;
+ lcdhw->lcddma_fb1_ceiling = gd->fb_base + FBSIZE(panel);
lcdhw->lcddma_ctrl = LCD_DMA_BURST_SIZE(LCD_DMA_BURST_16);

lcdhw->raster_timing0 = LCD_HORLSB(panel->hactive) |
@@ -179,8 +181,6 @@ int am335xfb_init(struct am335x_lcdpanel *panel)
LCD_TFT_MODE |
LCD_RASTER_ENABLE;

- gd->fb_base += 0x20; /* point fb behind palette */
-
debug("am335x-fb: waiting picture to be stable.\n.");
mdelay(panel->pon_delay);

--
2.8.0