[Intel-gfx] [PATCH 3/3] drm/i915: don't rewrite the GTT on resume

[Chris Wilson]

On Sun, 14 Oct 2012 19:10:38 -0700, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> The BIOS shouldn't be touching this memory across suspend/resume, so
> just leave it alone.  This saves us ~50ms on resume on my T420.
> 
> Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
> ---
>  drivers/gpu/drm/i915/i915_drv.c |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 824e3c8..95e2b8b 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -119,6 +119,10 @@ module_param_named(i915_enable_ppgtt, i915_enable_ppgtt, int, 0600);
>  MODULE_PARM_DESC(i915_enable_ppgtt,
>  		"Enable PPGTT (default: true)");
>  
> +int i915_needs_gtt_restore __read_mostly = 0;
> +module_param_named(gtt_restore, i915_needs_gtt_restore, int, 0600);
> +MODULE_PARM_DESC(gtt_restore, "Rewrite GTT on resume (default: false)");

Wrong way around. This code exists purely because KMS resume was broken
on a number of machines without reinitialising the GTT, ergo this is a
regression.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre