[Intel-gfx] [PATCH 2/2] drm/i915: ignore forcewake get/put when using vgpu

[Chris Wilson]

On Wed, Jan 25, 2017 at 02:04:56PM +0800, Weinan Li wrote:
> Host maintian the hardware's forcewake state, guest don't need and also
> can't control it. Although vgpu_read/write bypass forcewake_get/put in MMIO
> read/write, but still have separate path called by
> "intel_uncore_forcewake_get/put" and
> "intel_uncore_forcewake_get/put__locked". Unnecessary MMIO access in guest
> waste much CPU cost. Since we full virtualize the MMIO, just ignore the
> forcewake get/put in low level.

This patch is doing multiple things as you are altering a couple of
independent paths at the same time (fw control and mmio funcs).

>  static void
> +vgpu_fw_domains_get(struct drm_i915_private *dev_priv,
> +		    enum forcewake_domains fw_domains)
> +{
> +	/* Guest driver doesn't need to takes care forcewake. */;
> +}
> +
> +static void
> +vgpu_fw_domains_put(struct drm_i915_private *dev_priv,
> +		    enum forcewake_domains fw_domains)
> +{
> +	/* Guest driver doesn't need to takes care forcewake. */;
> +}

Or just 1 vgpu_fw_domains_nop()
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre