[Intel-gfx] [Patch 3/3_v2]: [DRM/I915] : Sync the default modes for LVDS output device

Jesse Barnes jbarnes at virtuousgeek.org
Wed Apr 1 22:34:20 CEST 2009

On Wed, 01 Apr 2009 13:27:02 -0700
Eric Anholt <eric at anholt.net> wrote:

> On Mon, 2009-03-23 at 11:30 +0800, yakui_zhao wrote:
> > Subject: [DRM/I915]: Sync the default modes for LVDS output device
> > From: Zhao Yakui <yakui.zhao at intel.com>
> > 
> > Sync the default modes for the LVDS output device
> >     This covers:
> >     Add the default modes for the LVDS output device.
> >     The bit of edid->feature.msc indicates whether the display
> > device is not continous-frequency. And it is used to determine
> > whether the default modes will be added to the output device.
> >     But for the LVDS output device the edid->feature.msc will
> > always be set.Even when there is no edid, the correponding bit in
> > the fake edid will be set. In such case the default modes will be
> > added to LVDS output device. If not, the different modes are
> > obtained by using KMS/UMS.
> > 
> > Signed-off-by: Zhao Yakui <yakui.zhao at intel.com>
> These giant tables of modes are insane.  Especially having a bunch of
> different refresh rates when the LVDS actually has a fixed refresh
> rate. Just generate a mode at each appropriate size using GTF or CVT.
> I'm not really sold on the whole idea of the kernel generating these
> fake modes for LVDS, given that we can support any size and that the
> refresh rate is a lie since we're always using the fixed mode.  Any
> other opinions on this?

Yeah, having a bunch of hard coded modes seems like the wrong way to do
things here.  We can support arbitrary sizes with panel fitting and/or
borders, so using CVT or GTF seems like a good idea.  Question is, how
do we indicate this to userland?  Ideally we'd just export a CVT/GTF
flag and allow just about any mode to be sent down at mode set time,
but that would probably mean changes to the way we handle modes in the
DRM core. Alternately, we could export the flag and let userland load
custom modes before using them (that would match the mode list handling
we have).

Jesse Barnes, Intel Open Source Technology Center

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