Re: [PATCH] drm/i915: BIOS and power context stolen mem handling for VLV v6

[Chris Wilson <chris@chris-wilson.co.uk>]

On Tue, May 07, 2013 at 02:34:31PM -0700, Jesse Barnes wrote:
> +static void valleyview_setup_pctx(struct drm_device *dev)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	struct drm_i915_gem_object *pctx;
> +	unsigned long pctx_paddr;
> +	u32 pcbr;
> +	int pctx_size = 24*1024;
> +
> +	pcbr = I915_READ(VLV_PCBR);
> +	if (pcbr) {
> +		/* BIOS set it up already, grab the pre-alloc'd space */
> +		int pcbr_offset;
> +
> +		pcbr_offset = (pcbr & (~4095)) - dev_priv->mm.stolen_base;
> +		pctx = i915_gem_object_create_stolen_for_preallocated(dev_priv->dev,
> +								      pcbr_offset,
> +								      pcbr_offset,
> +								      pctx_size);

We're reserving global GTT space here for someting that just looks like
it requires contiguous physical memory. This may cause issues if
something else is already bound to that GTT range. I think we want to
extend the interface to not reserve GTT space if gtt_offset == -1.

Much happier with the placement of functions and the comments help a
lot.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre