Re: HDMI timing parameters problem

[Geert Uytterhoeven <geert@linux-m68k.org>]

On Fri, Jun 4, 2010 at 17:27, Guennadi Liakhovetski
<g.liakhovetski@gmx.de> wrote:
> I'm trying to configure an HDMI controller on an ARM based SoC, and I
> cannot seem to find suitable values for blanking parameters.
>
> The monitor EDID reports 1280x1024@108MHz:
>
> H_ACTIVE = 1280
> H_SYNC_OFFSET = 48
> H_SYNC_WIDTH = 112
> H_BLANKING = 408
>
> V_ACTIVE = 1024
> V_SYNC_OFFSET = 1
> V_SYNC_WIDTH = 3
> V_BLANKING = 42
>
> The HDMI controller can be programmed in one of two modes: with a preset
> configuration or manually specifying each parameter. The only mode that
> somehow works up to now is the preset 1280x720@74.25MHz. With this mode
> the image on the monitor is stretched vertically, but it works.
> Unfortunately, the controller doesn't have any preset modes for 1280x1024
> or for anything close enough. So, I have to support manual geometry
> configuration. To reduce the number of required changes, as a first step,
> I'm trying to achieve the same result in manual mode, as I've got with
> preset, by programming 1280x720. For this I've chosen the following
> configuration:
>
>        .xres = 1280,
>        .yres = 720,
>        .left_margin = 224,
>        .right_margin = 104,
>        .hsync_len = 40,
>        .upper_margin = 20,
>        .lower_margin = 5,
>        .vsync_len = 5,
>
> which is the same, as what I'm configuring my LCD controller
> with. This translates to
>
> H_ACTIVE = 1280
> H_SYNC_OFFSET = 104
> H_SYNC_WIDTH = 40
> H_BLANKING = 368
>
> V_ACTIVE = 720
> V_SYNC_OFFSET = 5
> V_SYNC_WIDTH = 5
> V_BLANKING = 30
>
> With it the monitor recognises the signal, the LED goes green, but there's
> no image.
>
> I've done a few more tests with various configurations, but so far with no
> success. Can anyone suggest how to debug this? How to find the proper
> video mode?

The timings I calculated from the HDTV specs for ps3fb are slightly different.
But you may want to give them a try.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds