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

[Li, Weinan Z]

> -----Original Message-----
> From: Chris Wilson [mailto:chris at chris-wilson.co.uk]
> Sent: Wednesday, January 25, 2017 3:17 PM
> To: Li, Weinan Z <weinan.z.li at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; intel-gvt-dev at lists.freedesktop.org
> Subject: Re: [Intel-gfx] [PATCH 2/2] drm/i915: ignore forcewake get/put
> when using vgpu
> 
> 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).
> 
ok, let me separate 2 patches, 1 fw control, 2 remove vgpu_read/write 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()
vgpu_fw_domains_nop more simple and readable. 
> -Chris
> 
> --
> Chris Wilson, Intel Open Source Technology Centre