Re: [PATCH v2] drm/i915: set scanout buffer as uncached on Sandybridge

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

On Thu, 28 Oct 2010 14:16:09 +0800, Zhenyu Wang <zhenyuw@linux.intel.com> wrote:
> +	ret = i915_gem_object_enable_scanout(obj);
> +	if (ret) {
> +		kfree(intel_fb);
> +		return ERR_PTR(ret);
> +	}

We need to introduce a mutex_lock here. I wonder whether it is truly worth
it. Yes, user space often creates a fb for a new obj so we avoid the
unbind penalty on flipping to this fb. But that first rebind is a one-off
event as well, and we probably should look at how we can simply change
caching bits in the PTE on the fly.

In the short term I'll drop this hunk. I've pushed this to -staging as I'd
like to get another tested-by or reviewed-by and then send it to stable.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre