Hi Geert

On Fri, 4 Jun 2010, Geert Uytterhoeven wrote:

On Fri, Jun 4, 2010 at 17:27, Guennadi Liakhovetski
[off-list ref] wrote:

quoted

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.

You're referring to this mode from drivers/video/ps3fb.c:

    }, {
	/* SXGA */
	"sxga", 60, 1280, 1024, 9259, 248, 48, 38, 1, 112, 3,
	FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED,
	FB_MODE_IS_VESA
    }, {

right? Interestingly, those are exactly the values, that my monitor is 
reporting, also quoted at the top of this mail:

248 + 48 + 112 = 408
38 + 1 + 3 = 42

, and I cannot seem to get them to work:( hmm...

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/