[Intel-gfx] [PATCH 15/16] Revert "drm/i915: Allocate fbcon from stolen memory"

[chris at chris-wilson.co.uk]

On Tue, Aug 18, 2015 at 09:54:57PM +0000, Zanoni, Paulo R wrote:
> Em Sáb, 2015-08-15 às 09:24 +0100, Chris Wilson escreveu:
> > On Fri, Aug 14, 2015 at 06:34:20PM -0300, Paulo Zanoni wrote:
> > > This reverts commit 0ffb0ff283cca16f72caf29c44496d83b0c291fb.
> > > 
> > > Technology has evolved and now we have eDP panels with 3200x1800
> > > resolution. In the meantime, the BIOS guys didn't change the 
> > > default
> > > 32mb for stolen memory. And we can't assume our users will be able 
> > > to
> > > increase the default stolen memory size to more than 32mb - I'm not
> > > even sure all BIOSes allow that.
> > > 
> > > So just the fbcon buffer alone eats 22mb of my stolen memroy, and 
> > > due
> > > to the BDW/SKL restriction of not using the last 8mb of stolen 
> > > memory,
> > > all that's left for FBC is 2mb! Since fbcon is not the coolest 
> > > feature
> > > ever, I think it's better to save our precious stolen resource to 
> > > FBC
> > > and the other guys.
> > > 
> > > Besides, neither the original commit message nor the review 
> > > comments
> > > showed any arguments in favor of actually allocating fbcon from
> > > stolen.
> > 
> > Pardon?
> 
> 
> pzanoni at panetone:~/git/kernel/kernel$ git show
> 0ffb0ff283cca16f72caf29c44496d83b0c291fb | head -n 12
> commit 0ffb0ff283cca16f72caf29c44496d83b0c291fb
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Thu Nov 15 11:32:27 2012 +0000
> 
>     drm/i915: Allocate fbcon from stolen memory
>     
>     Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>     Reviewed-by: Jesse Barnes <jbarnes at virtuousgeek.org>
>     Acked-by: Ben Widawsky <ben at bwidawsk.net>
>     Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> 
> diff --git a/drivers/gpu/drm/i915/intel_fb.c
> b/drivers/gpu/drm/i915/intel_fb.c
> pzanoni at panetone:~/git/kernel/kernel$ 

Sorry, I though it was pretty self explanatory that we want to reuse as
much as stolen as is possible on all machines, epecially those where
even 8MiB reserved is about 10% of available memory. So not using it for
pinned memory is a double whammy.

That would have been said in the preceeding patches to enable stolen
memory.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre