[Intel-gfx] [PATCH] drm/i915: fix screen blank issue in TV detect

[Zhenyu Wang]

On 2009.09.18 15:32:42 -0700, Jesse Barnes wrote:
> On Mon, 14 Sep 2009 10:06:01 +0800
> Zhenyu Wang <zhenyuw at linux.intel.com> wrote:
> 
> > On 2009.09.11 10:51:06 -0700, Eric Anholt wrote:
> > > On Fri, 2009-09-11 at 13:19 +0800, Zhenyu Wang wrote:
> > > > In load time, this one trys to detect TV by current encoder state
> > > > instead of load-detect method. Because load-detect will set mode
> > > > which disable VGA mode entirely, but couldn't restore back later.
> > > > Destroy VGA mode which is the mode after system boot caused black
> > > > screen problem, although load fbcon or X later could setup the
> > > > mode on LVDS without problem.
> > > > 
> > > > That fixes screen blank issue seen on Macbook after boot and
> > > > before fbcon or X kicks in, actually this affects all laptops
> > > > with TV out, or without real port but our TV encoder probe fails
> > > > to detect.
> > > > 
> > > > Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
> > > 
> > > I think a black screen after boot and before fbcon loads sounds
> > > like the right behavior.
> > > 
> > 
> > Really? So this looks like you want to force fbcon loading for kernel,
> > I also thought that way, but I don't know if we can do that in i915
> > module?
> 
> No, we don't need to force it.  It's up to the distro to load things at
> the right time.
> 

Well, yeah, you may prefer that way, but I don't think all distros do that automaticly.
Debian doesn't do that for me after I build my own kernel and modules on MacBook...

We've already known that it'll be blank in the way, and we might be got more
bug reports like http://bugs.freedesktop.org/show_bug.cgi?id=24021, why we can't
just check the current hw status in load time instead of doing load_detect? Just
realized that for older 8xx chips we also do load_detect for CRT, I can refresh
my origin patch to not do any load_detect when loading.

-- 
Open Source Technology Center, Intel ltd.

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