Re: [PATCH] drm/amd/display: Limit DCN to x86 arch

From: "Michel Dänzer" <michel-otUistvHUpPR7s880joybQ@public.gmane.org>
To: "Harry Wentland" <harry.wentland-5C7GfCeVMHo@public.gmane.org>,
	"Christian König"
	<deathsimple-ANTagKRnAhcb1SvskN2V4Q@public.gmane.org>,
	"Dave Airlie" <airlied-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: "Michel Dänzer" <michel.daenzer-5C7GfCeVMHo@public.gmane.org>,
	"amd-gfx mailing list"
	<amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>,
	"Dmytro Laktyushkin"
	<Dmytro.Laktyushkin-5C7GfCeVMHo@public.gmane.org>,
	"Alex Deucher" <Alexander.Deucher-5C7GfCeVMHo@public.gmane.org>,
	"Tony Cheng" <Tony.Cheng-5C7GfCeVMHo@public.gmane.org>,
	"Christian König" <christian.koenig-5C7GfCeVMHo@public.gmane.org>
Subject: Re: [PATCH] drm/amd/display: Limit DCN to x86 arch
Date: Wed, 24 May 2017 10:09:00 +0900	[thread overview]
Message-ID: <4905eb15-ec8c-61f7-f295-1e014009041c@daenzer.net> (raw)
In-Reply-To: <ff8918ec-ee0e-692e-4ada-cd6bd939d902-5C7GfCeVMHo@public.gmane.org>

On 23/05/17 10:37 PM, Harry Wentland wrote:
> On 2017-05-20 04:13 AM, Christian König wrote:
>> Am 19.05.2017 um 22:28 schrieb Harry Wentland:
>>> 
>>> I realize this is raising a lot of concern. I was concerned myself
>>> when I first saw this. Beside calling kernel_fpu_begin() and
>>> kernel_fpu_end() are there other things to watch out for?
>>
>> Yeah, especially setting "-msse" is rather questionable. As far as I
>> know on 64bit systems it is the default, but on 32bit systems that
>> could silently break some assumptions.
>>
>> Additional to that as far as I know "-msse" is just for optimization
>> and that isn't performance critical code, so why exactly do we need it?
> 
> Once we enable multi-plane code this code becomes performance critical
> as I believe it gets executed when resizing an underlay surface, such as
> a video player.

That should still only happen once per frame though, i.e. on the order
of 10s to 100s of times per second.

-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer
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