radeon kms, LCD timing info

[Alex Deucher]

On Sat, Oct 31, 2009 at 6:41 PM, Howard Chu <hyc at symas.com> wrote:
> I have an HP dv5z laptop with HD3450 GPU. It came with a 1680x1050 LCD panel
> and I'm currently trying to use a 1920x1200 panel instead. The panel that I
> have seems to work fine as far as booting and text mode goes, but when I start
> up X I get a black screen. By the way, this is currently running Ubuntu Jaunty
> but with a self-compiled 2.6.32-rc4 kernel and X stuff from the xorg-edgers
> ppa, so fairly bleeding edge driver and mesa.
>
> Another interesting bit is that with the fbcon driver, the VTs also work fine,
> and I have 75 rows x 240 columns of text. So it appears that the radeon driver
> is using acceptable timing parameters at startup, but when the X server starts
> it switches to a set of timing parameters that don't work.
>
> First question: how do I find out what timing parameters are in use at boot,
> and what's in use by radeon+fbcon?
>
> Second question: how do I set the correct timing parameters while X is
> running? Just playing with modelines doesn't seem to be sufficient. X boots up
> with several modelines but most of them are defective. E.g., 1920x1080
> actually displays the desktop instead of just a black screen, but it is
> shifted right by about an inch, and has a cyclic fade-to-white going on. Many
> of the other modes do the same thing, and a few (like 640x480) just display black.
>
> Any help would be much appreciated, thanks.

Please post your xorg log and dmesg output.  The driver gets the panel
timing information from a table in the bios.  With the new panel, the
driver is probably still getting the old timing from the vbios.

Alex