From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Hackmann Subject: Re: [RFC v2 5/8] drm/fence: add in-fences support Date: Fri, 29 Apr 2016 14:14:31 -0700 Message-ID: <5723CEB7.8090609@google.com> References: <20160426101050.GN4329@intel.com> <20160426141422.GG7857@joana> <20160426143635.GW8291@phenom.ffwll.local> <20160426162621.GU4329@intel.com> <20160426172049.GB2558@phenom.ffwll.local> <20160426174045.GC4329@intel.com> <20160426182346.GC2558@phenom.ffwll.local> <20160426185506.GH4329@intel.com> <20160426200505.GD2558@phenom.ffwll.local> <571FD402.6050407@google.com> <20160427063904.GH2558@phenom.ffwll.local> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: Received: from mail-pf0-x22b.google.com (mail-pf0-x22b.google.com [IPv6:2607:f8b0:400e:c00::22b]) by gabe.freedesktop.org (Postfix) with ESMTPS id 613206E409 for ; Fri, 29 Apr 2016 21:14:34 +0000 (UTC) Received: by mail-pf0-x22b.google.com with SMTP id y69so52897477pfb.1 for ; Fri, 29 Apr 2016 14:14:34 -0700 (PDT) In-Reply-To: <20160427063904.GH2558@phenom.ffwll.local> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= , Gustavo Padovan , Gustavo Padovan , Daniel Stone , Riley Andrews , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, =?UTF-8?Q?Arve_Hj=c3=b8nnev=c3=a5g?= , John Harrison List-Id: dri-devel@lists.freedesktop.org T24gMDQvMjYvMjAxNiAxMTozOSBQTSwgRGFuaWVsIFZldHRlciB3cm90ZToKPj4gQSAocGVyLUNS VEM/KSBhcnJheSBvZiBmZW5jZXMgd291bGQgYmUgbW9yZSBmbGV4aWJsZS4gIEFuZCBldmVuIGlu IHRoZSBjYXNlcwo+PiB3aGVyZSB5b3UgY291bGQgbWFrZSBhIDEtdG8tMSBtYXBwaW5nIGJldHdl ZW4gcGxhbmVzIGFuZCBmZW5jZXMsIGl0J3Mgbm90Cj4+IHRoYXQgbXVjaCBtb3JlIHdvcmsgZm9y IHVzZXJzcGFjZSB0byBhc3NlbWJsZSB0aG9zZSBmZW5jZXMgaW50byBhbiBhcnJheQo+PiBhbnl3 YXkuCj4KPiBJJ20gb2sgd2l0aCBhbiBhcnJheSB0b28gaWYgdGhhdCdzIHdoYXQgeW91IGZvbGtz IHByZWZlciAoaXQncyBtZWFudCB0byBiZQo+IHVzZWQgYnkgeW91IGFmdGVyIGFsbCkuIEkganVz dCBkb24ndCB3YW50IGp1c3QgMSBmZW5jZSBmb3IgdGhlIGVudGlyZSBvcCwKPiBmb3JjaW5nIHVz ZXJzcGFjZSB0byBmaXJzdCBtZXJnZSB0aGVtIGFsbCB0b2dldGhlci4gVGhhdCBzZWVtcyBzaWxs eS4KPgo+IE9uZSBzaWRlLWVmZmVjdCBvZiB0aGF0IGlzIHRoYXQgd2UnZCBhbHNvIGhhdmUgdG8g cmV3b3JrIGFsbCB0aGUgaW50ZXJuYWwKPiBiaXRzIGFuZCBtb3ZlIGZlbmNlcyBhcm91bmQgaW4g YXRvbWljLiBXaGljaCBtZWFucyBjaGFuZ2UgYSBwaWxlIG9mCj4gZHJpdmVycy4gTm90IHN1cmUg dGhhdCdzIHdvcnRoIGl0LCBidXQgSSdkIGJlIG9rIGVpdGhlciB3YXkgcmVhbGx5Lgo+IC1EYW5p ZWwKPgoKSXQncyBub3QgYSBzdHJvbmcgcHJlZmVyZW5jZSBvbiBteSBlbmQuICBUaGUgMToxIHBs YW5lLXRvLWxheWVyIG1hcHBpbmcgCmJyZWFrcyBkb3duIHNvbWV3aGF0IG9uIGhhcmR3YXJlIHdo ZXJlIHlvdSBuZWVkIHRvIHNwbGl0IGxhcmdlIApod2NvbXBvc2VyIGxheWVycyBhY3Jvc3MgbXVs dGlwbGUgRFJNIHBsYW5lcy4KClRoYXQgc2FpZCwgeW91IGNhbiBmb3JjZSB0aGF0IGNhc2UgdG8g Zml0IGJ5IGp1c3QgZHVwKClpbmcgdGhlIGZlbmNlIGEgCmJ1bmNoIG9mIHRpbWVzIG9yIGFyYml0 cmFyaWx5IHBpY2tpbmcgb25lIG9mIHRoZSBwbGFuZXMgdG8gYXNzaWduIHRoZSAKZmVuY2UgdG8u ICBFaXRoZXIgaXMga2x1ZGdleSwgYnV0IEkgY2FuJ3QgYXJndWUgaXQncyBrbHVkZ2V5IGVub3Vn aCB0byAKanVzdGlmeSByZWZhY3RvcmluZyBhIGJ1bmNoIG9mIGV4aXN0aW5nIGRyaXZlciBjb2Rl LgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpkcmktZGV2 ZWwgbWFpbGluZyBsaXN0CmRyaS1kZXZlbEBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0cHM6Ly9s aXN0cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9kcmktZGV2ZWwK From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752668AbcD2VOf (ORCPT ); Fri, 29 Apr 2016 17:14:35 -0400 Received: from mail-pf0-f178.google.com ([209.85.192.178]:33390 "EHLO mail-pf0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751829AbcD2VOd (ORCPT ); Fri, 29 Apr 2016 17:14:33 -0400 Subject: Re: [RFC v2 5/8] drm/fence: add in-fences support To: =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= , Gustavo Padovan , Gustavo Padovan , Daniel Stone , Riley Andrews , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, =?UTF-8?Q?Arve_Hj=c3=b8nnev=c3=a5g?= , John Harrison References: <20160426101050.GN4329@intel.com> <20160426141422.GG7857@joana> <20160426143635.GW8291@phenom.ffwll.local> <20160426162621.GU4329@intel.com> <20160426172049.GB2558@phenom.ffwll.local> <20160426174045.GC4329@intel.com> <20160426182346.GC2558@phenom.ffwll.local> <20160426185506.GH4329@intel.com> <20160426200505.GD2558@phenom.ffwll.local> <571FD402.6050407@google.com> <20160427063904.GH2558@phenom.ffwll.local> From: Greg Hackmann Message-ID: <5723CEB7.8090609@google.com> Date: Fri, 29 Apr 2016 14:14:31 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20160427063904.GH2558@phenom.ffwll.local> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/26/2016 11:39 PM, Daniel Vetter wrote: >> A (per-CRTC?) array of fences would be more flexible. And even in the cases >> where you could make a 1-to-1 mapping between planes and fences, it's not >> that much more work for userspace to assemble those fences into an array >> anyway. > > I'm ok with an array too if that's what you folks prefer (it's meant to be > used by you after all). I just don't want just 1 fence for the entire op, > forcing userspace to first merge them all together. That seems silly. > > One side-effect of that is that we'd also have to rework all the internal > bits and move fences around in atomic. Which means change a pile of > drivers. Not sure that's worth it, but I'd be ok either way really. > -Daniel > It's not a strong preference on my end. The 1:1 plane-to-layer mapping breaks down somewhat on hardware where you need to split large hwcomposer layers across multiple DRM planes. That said, you can force that case to fit by just dup()ing the fence a bunch of times or arbitrarily picking one of the planes to assign the fence to. Either is kludgey, but I can't argue it's kludgey enough to justify refactoring a bunch of existing driver code.