Re: [PATCH 1/2] drm/ttm: remove unused placement flags

From: "Christian König" <deathsimple-ANTagKRnAhcb1SvskN2V4Q@public.gmane.org>
To: Emil Velikov <emil.l.velikov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: "Zhou,
	David(ChunMing)" <David1.Zhou-5C7GfCeVMHo@public.gmane.org>,
	"dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org"
	<dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>,
	"amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org"
	<amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>,
	"Cui, Flora" <Flora.Cui-5C7GfCeVMHo@public.gmane.org>,
	"Koenig,
	Christian" <Christian.Koenig-5C7GfCeVMHo@public.gmane.org>,
	"Zhang, Hawking" <Hawking.Zhang-5C7GfCeVMHo@public.gmane.org>
Subject: Re: [PATCH 1/2] drm/ttm: remove unused placement flags
Date: Fri, 9 Sep 2016 16:30:11 +0200	[thread overview]
Message-ID: <cf57189a-e3e9-a913-0a5f-0fa799eb9c23@vodafone.de> (raw)
In-Reply-To: <CACvgo53AAEsxAoQvAe=ffMnQiZiE=MPWne2Abg=rAt4bRkK8NQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

Am 09.09.2016 um 15:54 schrieb Emil Velikov:
> On 9 September 2016 at 12:24, Christian König <deathsimple@vodafone.de> wrote:
>> Hi Hawking,
>>
>>> Removing the flag will make ttm_mem_type_from_place skip counting the
>>> corresponding placement and thus have impact on mem region create and bo
>>> movement.
>> And that is exactly the reason why I want to remove the unused flags.
>>
>>> There is no guarantee that amdgpu would never introduce new memory domain
>>> in future.
>> Irrelevant, if any driver wants to use additional domains it should add them
>> when they are used.
>>
>> BTW: Why would we want to add another TTM domain? I really don't see any
>> need for that.
>>
>>> Then how about keep these flags?
>> Actually we used to have automated scanners which complain about unused
>> code. I'm wondering why they don't detected that earlier.
>>
>> Anyway any code which isn't used in a while should be removed.
>>
> Fwiw I second Christian here. If they are unused in open-source
> drivers there's no reason to keep them.
> If/as that changes the (newly introduced) user can add back the relevant code.

Crap to late :( I was about to send a V2 of the patch to keep the PRIV 
flags.

> If closed-source driver(s) use them, then they can keep it as part of
> their blob. Upstream kernel does not cater for closed-source drivers,
> period.
> I realise that's not the answer some are hoping for, so if you want to
> question it take it up with Linus and co.

It's not an issue between closed vs. open, but rather additional work of 
rebasing the open code when we start to use additional domains.

But on the other hand I still haven't seen a good reason for using 
those. As far as I know we have covered all resource in the current and 
next hardware generation with the existing flags.

Regards,
Christian.

> Regards,
> Emil

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