[Intel-gfx] [PATCH] drm/i915: Put all permanent stolen allocations together

[Chris Wilson]

Quoting Ville Syrjälä (2018-09-11 16:31:56)
> On Tue, Sep 11, 2018 at 04:14:39PM +0100, Chris Wilson wrote:
> > Whilst reviewing another new user of stolen memory, Ville made the
> > observation that we should try to ensure that all permanent allocations
> > within stolen memory are clustered together at either end of the stolen
> > region, in order to reduce fragmentation. In the depths of
> > i915_gem_stolen.c it is not always clear what manner of allocation we
> > need, so expose the drm_mm search parameter and push the decision to our
> > callers.
> > 
> > Suggested-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.h         | 15 +++++++++------
> >  drivers/gpu/drm/i915/i915_gem_stolen.c  | 19 ++++++++++++-------
> >  drivers/gpu/drm/i915/intel_engine_cs.c  |  3 ++-
> >  drivers/gpu/drm/i915/intel_fbc.c        | 13 ++++++++-----
> >  drivers/gpu/drm/i915/intel_fbdev.c      |  3 ++-
> >  drivers/gpu/drm/i915/intel_overlay.c    |  3 ++-
> >  drivers/gpu/drm/i915/intel_pm.c         |  3 ++-
> >  drivers/gpu/drm/i915/intel_ringbuffer.c |  2 +-
> >  8 files changed, 38 insertions(+), 23 deletions(-)
> > 
> <snip>
> > diff --git a/drivers/gpu/drm/i915/intel_overlay.c b/drivers/gpu/drm/i915/intel_overlay.c
> > index 72eb7e48e8bc..b134b9cabf93 100644
> > --- a/drivers/gpu/drm/i915/intel_overlay.c
> > +++ b/drivers/gpu/drm/i915/intel_overlay.c
> > @@ -1306,7 +1306,8 @@ static int get_registers(struct intel_overlay *overlay, bool use_phys)
> >       struct i915_vma *vma;
> >       int err;
> >  
> > -     obj = i915_gem_object_create_stolen(overlay->i915, PAGE_SIZE);
> > +     obj = i915_gem_object_create_stolen(overlay->i915,
> > +                                         PAGE_SIZE, DRM_MM_INSERT_LOW);
> 
> Won't these early INSERT_LOWs create problems for the BIOS fb takeover?

The BIOS reservation is the very first thing we do, right? The sequence
is meant to be init the drm_mm, probe all the HW state (BIOS fb, vlv
pctx, anything else?) and make the reservations, then finish
initialising the unreserved portions before allowing ourselves to
allocate from it.
-Chris