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

[yakui_zhao]

On Thu, 2009-04-02 at 04:38 +0800, Alex Deucher wrote:
> On 4/1/09, 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?
> >
It is inappropriate to add such a giant table in LVDS. In fact I spend
much time  copying such a table from the file of xf86DefModeSet.c. (In
the Xserver the default modes are generated by using scripts).

If the default Vesa mode is not added, the different modes will be
obtained by using KMS/UMS. And then the user can't adjust the output
mode and report that this is a bug. So IMO it is useful to add the
default modes. 
The question is how to add it. Is the default mode generated by using
CVT/GTF in kernel mode or export the flag of CVT/GFT to userland?


I agree with What Alex said. Maybe the common drm mode function helper
should add a bunch of common modes , which can be called by the output
device like LVDS. Most users won't add a new mode for the output device.
They depend on the modes that are reported by xrandr tool. 
> 
> Maybe a common drm mode function helper that will add a bunch of
> common (4:3 and 16:9) modes that fixed mode encoders like LVDS can
> call.  We certainly don't need to add modes with differing refresh
> rates.
> 
> Alex
> 
> >
> >  --
> >  Eric Anholt
> >  eric at anholt.net                         eric.anholt at intel.com
> >
> >
> >
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