[Intel-gfx] [PATCH 05/12] drm/i915: Fix DRAM size reporting for BXT

[Ville Syrjälä]

On Mon, Feb 25, 2019 at 08:35:08PM +0000, Chris Wilson wrote:
> Quoting Ville Syrjala (2019-02-25 20:29:00)
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > The BXT DUNIT register tells us the size of each DRAM device
> > in Gb. We want to report the size of the whole DIMM in GB, so
> > that it matches how we report it for non-LP platforms.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> > index 1f4a966a9727..c40a738dabd3 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.c
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -1322,7 +1322,14 @@ bxt_get_dram_info(struct drm_i915_private *dev_priv)
> >                 width = bxt_get_dimm_width(val);
> >                 ranks = bxt_get_dimm_ranks(val);
> >  
> > -               DRM_DEBUG_KMS("CH%d DIMM size: % dGB, width: X%d, ranks:%d\n",
> > +               /*
> > +                * Size in register is Gb per DRAM device.
> > +                * Convert to total GB to match the way
> > +                * we report this for non-LP platforms.
> > +                */
> > +               size = size * ranks * 8 / (width ?: 1);
> 
> Should it be /8 for Gbits to GBytes?

It's a hand optimized version of

size*ranks*64 / width / 8

-- 
Ville Syrjälä
Intel