From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jesse Barnes <jbarnes@virtuousgeek.org>
Subject: Re: [PATCH 55/62] drm/i915/bdw: Disable semaphores
Date: Mon, 4 Nov 2013 10:18:43 -0800
Message-ID: <20131104101843.662e1ed0@jbarnes-desktop>
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To: Ben Widawsky <benjamin.widawsky@intel.com>
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On Sat,  2 Nov 2013 21:07:53 -0700
Ben Widawsky <benjamin.widawsky@intel.com> wrote:

> From: Ben Widawsky <ben@bwidawsk.net>
> 
> We've done insufficient testing on them thus far, so keep them disabled
> until we do test.
> 
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> ---
>  drivers/gpu/drm/i915/i915_drv.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 590d999..efb63b0 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -478,6 +478,12 @@ bool i915_semaphore_is_enabled(struct drm_device *dev)
>  	if (INTEL_INFO(dev)->gen < 6)
>  		return 0;
>  
> +	/* Until we get further testing... */
> +	if (IS_GEN8(dev)) {
> +		DRM_INFO("Semaphores disabled GEN8\n");
> +		return 0;
> +	}
> +
>  	if (i915_semaphores >= 0)
>  		return i915_semaphores;
>  

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Side note; for stuff like this where we disable a critical feature
(e.g. PPGTT, semaphores) with the intention of enabling it later, maybe
we should do a WARN or something if preliminary hw support is enabled.
Or somehow catch it so we have to address it before declaring the bits
good.

-- 
Jesse Barnes, Intel Open Source Technology Center