Framebuffer size for 24bpp

Technical Support
, , ,
1

Hello,
I have a some problem with 24bpp RGB output.
It seems, the framebuffer size have some limitations:

If I set framebuffer to 16bpp, fbset reports correct size:
video=tegrafb0:pixclockpol:0,outputen:1,1920x1080@60

root@colibri-t30:~# fbset

mode "1920x1080-60"
    # D: 148.500 MHz, H: 67.500 kHz, V: 60.000 Hz
    geometry 1920 1080 1920 2160 16
    timings 6734 148 88 36 4 44 5
    hsync high
    vsync high
    rgba 5/11,6/5,5/0,0/0
endmode

If I set 24bpp mode, framebuffer is smaller then my desired resolution:
vidargs=video=tegrafb0:pixclockpol:0,outputen:1,1920x1080-24@60

root@colibri-t30:~# fbset

mode "1400x1050-60"
    # D: 108.003 MHz, H: 63.983 kHz, V: 59.965 Hz
    geometry 1400 1050 1400 2100 32
    timings 9259 136 40 13 1 112 3
    rgba 8/0,8/8,8/16,8/24
endmode

Is there any connection between frambuffer settings and Xorg rendering? Xorg config is the same in this two cases, but painting on display is totally damaged (any small screens with incorrect offset)

In both cases colours is damaged well.

Kernel diff:

--- a/arch/arm/mach-tegra/board-colibri_t30-panel.c
+++ b/arch/arm/mach-tegra/board-colibri_t30-panel.c
@@ -239,6 +239,8 @@ static struct tegra_dc_out_pin colibri_t30_dc_out_pins[] = {
        },
 };
 
+
+
 static struct tegra_dc_out colibri_t30_disp1_out = {
        .type                   = TEGRA_DC_OUT_RGB,
        .parent_clk             = "pll_d_out0",
@@ -246,7 +248,7 @@ static struct tegra_dc_out colibri_t30_disp1_out = {
 
        .align                  = TEGRA_DC_ALIGN_MSB,
        .order                  = TEGRA_DC_ORDER_RED_BLUE,
-       .depth                  = 18,
+       .depth                  = 24,
        .dither                 = TEGRA_DC_ORDERED_DITHER,
 
        /* Use 32-bit depth for android builds */
2

And you consulted the following article on our developer website?

3

Yes, of course, but i didn’t see any limitations for that. It only contains info about hard-coded 18bpp output in kernel, so I changed this for 24bpp. No info about fullhd resolution and 24bpp.

4

Hi @msv_zitnik

Which display are you using?
Could you provide a datasheet?
Which Interface are you using to connect this display?

In both cases colours is damaged well.

This looks like that the cabling is wrong. Could you provide the schematic of the display connection?

Best regards,
Jaski

5

@msv_zitnik:
arch/arm/mach-tegra/board-colibri_t30.c

Change
tegra_reserve(0, SZ_8M + SZ_1M, SZ_16M);
to
tegra_reserve(0, SZ_16M, SZ_16M);