[Intel-gfx] [PATCH 1/2] drm/i915: Try to allocate more memory for FBC on Ironlake or GM45

[Jesse Barnes]

On Wed, 24 Mar 2010 12:57:41 -0700
Eric Anholt <eric at anholt.net> wrote:

> On Tue, 23 Mar 2010 11:12:32 +0800, Zhenyu Wang <zhenyuw at linux.intel.com> wrote:
> > From: Zhao Yakui <yakui.zhao at intel.com>
> > 
> > The framebuffer compression can support up to 2K lines and 4K pixels, which
> > means that it can support up to 32M memory space. But now it is only limited
> > to 8M.
> > 
> > Try to allocate more memory for FBC from the stolen memory on Ironlake or
> > GM45.
> > 
> > Signed-off-by: Zhao Yakui <yakui.zhao at intel.com>
> > Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_dma.c      |   16 +++++++++++++---
> >  drivers/gpu/drm/i915/intel_display.c |   10 ++++++++--
> >  2 files changed, 21 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> > index 902d286..61fb967 100644
> > --- a/drivers/gpu/drm/i915/i915_dma.c
> > +++ b/drivers/gpu/drm/i915/i915_dma.c
> > @@ -1451,9 +1451,19 @@ static int i915_load_modeset_init(struct drm_device *dev,
> >  		int cfb_size;
> >  
> >  		/* Try to get an 8M buffer... */
> > -		if (prealloc_size > (9*1024*1024))
> > -			cfb_size = 8*1024*1024;
> > -		else /* fall back to 7/8 of the stolen space */
> > +		if (prealloc_size > (9*1024*1024)) {
> > +			if (IS_GM45(dev) || IS_IRONLAKE_M(dev)) {
> > +				if (prealloc_size >= (64 * 1024 * 1024))
> > +					cfb_size = 32 * 1024 * 1024;
> > +				else if (prealloc_size >= (32 * 1024 * 1024))
> > +					cfb_size = 24 * 1024 * 1024;
> > +				else if (prealloc_size >= (16 * 1024 * 1024))
> > +					cfb_size = 12 * 1024 * 1024;
> > +				else
> > +					cfb_size = 8 * 1024 * 1024;
> > +			} else
> > +				cfb_size = 8*1024*1024;
> > +		} else /* fall back to 7/8 of the stolen space */
> >  			cfb_size = prealloc_size * 7 / 8;
> >  		i915_setup_compression(dev, cfb_size);
> 
> The previous code was "use 7/8 of stolen space, unless we've got a ton
> in which case limit it to 8MB."  Now your code has a ton of cases to use
> 4/8MB increments.  Why 4/8MB increments?  From the commit message, I
> would have expected:
> 
> cfb_size = prealloc_size * 7 / 8;
> if (IS_GM45(dev) || IS_IRONLAKE_M(dev)) {
>    if (cfb_size > (32 * 1024 * 1024))
>       cfb_size = 32 * 1024 * 1024;
> } else {
>    if (cfb_size > (8 * 1024 * 1024))
>       cfb_size = 8 * 1024 * 1024;
> }

Yeah, that logic looks better.  We could even make it a module param to
allow override (e.g. if a user only needed an 8M buffer and wanted to
let the OS have the rest).

-- 
Jesse Barnes, Intel Open Source Technology Center