From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= Subject: Re: [PATCH v2] drm/color: Document CTM eqations Date: Fri, 17 Feb 2017 17:16:56 +0200 Message-ID: <20170217151656.GV31595@intel.com> References: <20170131151828.GU31595@intel.com> <20170131153928.GB11506@e106950-lin.cambridge.arm.com> <20170131172215.GV31595@intel.com> <20170215113959.GT31595@intel.com> <20170217135451.GA18487@e106950-lin.cambridge.arm.com> <20170217145643.GU31595@intel.com> <492eec8f-a45e-190c-469f-018c82053f7f@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by gabe.freedesktop.org (Postfix) with ESMTPS id 864E16E328 for ; Fri, 17 Feb 2017 15:17:15 +0000 (UTC) Content-Disposition: inline In-Reply-To: <492eec8f-a45e-190c-469f-018c82053f7f@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Lionel Landwerlin Cc: Daniel Vetter , Linux Kernel Mailing List , dri-devel List-Id: dri-devel@lists.freedesktop.org T24gRnJpLCBGZWIgMTcsIDIwMTcgYXQgMDM6MDU6MjhQTSArMDAwMCwgTGlvbmVsIExhbmR3ZXJs aW4gd3JvdGU6Cj4gT24gMTcvMDIvMTcgMTQ6NTYsIFZpbGxlIFN5cmrDpGzDpCB3cm90ZToKPiA+ IE9uIEZyaSwgRmViIDE3LCAyMDE3IGF0IDAyOjQyOjI2UE0gKzAwMDAsIExpb25lbCBMYW5kd2Vy bGluIHdyb3RlOgo+ID4+IE9uIDE3LzAyLzE3IDEzOjU0LCBCcmlhbiBTdGFya2V5IHdyb3RlOgo+ ID4+PiBXaGF0J3MgdGhlIHZlcmRpY3Q/IFdlJ3ZlIGdvdCBbMV0gd2hpY2ggaXMgYWJvdXQgdG8g YmVjb21lIGFub3RoZXIKPiA+Pj4gKGRyaXZlcikgaW1wbGVtZW50YXRpb24gLSBiZXR0ZXIgdG8g Y2hhbmdlIGJlZm9yZSB0aGF0IG1lcmdlcyB0aGFuCj4gPj4+IGFmdGVyIEkgZ3Vlc3MuCj4gPj4+ Cj4gPj4+IC1Ccmlhbgo+ID4+Pgo+ID4+PiBbMV0gaHR0cHM6Ly9sa21sLm9yZy9sa21sLzIwMTcv Mi8xMy8zMDQKPiA+Pj4KPiA+Pj4gT24gV2VkLCBGZWIgMTUsIDIwMTcgYXQgMTE6NTY6NTVBTSAr MDAwMCwgRGFuaWVsIFN0b25lIHdyb3RlOgo+ID4+Pj4gSGksCj4gPj4+Pgo+ID4+Pj4gT24gMTUg RmVicnVhcnkgMjAxNyBhdCAxMTozOSwgVmlsbGUgU3lyasOkbMOkCj4gPj4+PiA8dmlsbGUuc3ly amFsYUBsaW51eC5pbnRlbC5jb20+IHdyb3RlOgo+ID4+Pj4+IE9uIFR1ZSwgSmFuIDMxLCAyMDE3 IGF0IDA2OjQ2OjM5UE0gKzAxMDAsIERhbmllbCBWZXR0ZXIgd3JvdGU6Cj4gPj4+Pj4+IE9uIFR1 ZSwgSmFuIDMxLCAyMDE3IGF0IDY6MjIgUE0sIFZpbGxlIFN5cmrDpGzDpAo+ID4+Pj4+PiA8dmls bGUuc3lyamFsYUBsaW51eC5pbnRlbC5jb20+IHdyb3RlOgo+ID4+Pj4+Pj4gSG1tLiBUd28ncyBj b21wbGVtZW50IGlzIHdoYXQgSSB3YXMgdGhpbmtpbmcgaXQgaXMuIFdoaWNoIHNob3dzIHRoYXQK PiA+Pj4+Pj4+IEkgbmV2ZXIgbWFuYWdlZCB0byByZWFkIHRoZSBjb2RlIGluIGFueSBkZXRhaWwu IERlZmluaXRlbHkgbmVlZHMgdG8KPiA+Pj4+Pj4+IGJlIGRvY3VtZW50ZWQgcHJvcGVybHkuCj4g Pj4+Pj4+IFRoYXQgc291bmRzIHN1cHJlbWVseSBiYWNrd2FyZHMuIEkgZ3Vlc3Mgd2UgY2FuJ3Qg Zml4IHRoaXMgYW55bW9yZT8KPiA+Pj4+PiBJIGhhdmUgbm8gaWRlYS4gQW55b25lIGVsc2U/Cj4g Pj4+PiBJIGRvbid0IGtub3cgb2YgYW55IGltcGxlbWVudGF0aW9uIHVzaW5nIHRoaXM7IG1heWJl IGNsb3NlZCBJbnRlbAo+ID4+Pj4gQW5kcm9pZCBzdHVmZj8gQ2VydGFpbmx5IEdpdEh1YiBzaG93 ZWQgbm8tb25lIHVzaW5nIGl0LCBhbmQgbmVpdGhlciBYCj4gPj4+PiBub3IgV2VzdG9uL011dHRl ciBhcmUgdXNpbmcgaXQgeWV0Lgo+ID4+Pj4KPiA+Pj4+IENoZWVycywKPiA+Pj4+IERhbmllbAo+ ID4+IElmIHdlJ3JlIHRhbGtpbmcgZml4ZWQgcG9pbnQgcmVwcnNlbnRhdGlvbiwgQ2hyb21lT1Mg aXMgdXNpbmcgdGhpcyA6Cj4gPj4KPiA+PiBodHRwczovL2NzLmNocm9taXVtLm9yZy9jaHJvbWl1 bS9zcmMvdWkvb3pvbmUvcGxhdGZvcm0vZHJtL2dwdS9kcm1fZGV2aWNlLmNjP3E9RHJtRGV2aWNl Jmw9MjA5Cj4gPiBTbyBpdCdzIGFscmVhZHkgdXNpbmcgdGhlIHNpZ24rbWFnbml0dWRlIHN0dWZm LiBXaGljaCBwcmVzdW1hYmx5Cj4gPiBtZWFucyB3ZSBjYW4ndCBjaGFuZ2UgaXQgdG8gdHdvJ3Mg Y29tcGxlbWVudCBhbnltb3JlIDooIE1heWJlIHdlIGFkZCBhCj4gPiBDVE0yIHByb3BlcnR5IDsp Cj4gPgo+ID4gVXNpbmcgc2lnbittYWduaXR1ZGUgZGVmaW5pdGVseSBsb29rcyByYXRoZXIgaW5l ZmZpY2llbnQgc2luY2UgdGhlcmUncwo+ID4gYSBicmFuY2ggaW5zaWRlIHRoZSBsb29wLiBXaXRo IHR3bydzIGNvbXBsZW1lbnQgeW91IHdvdWxkbid0IG5lZWQgdGhhdAo+ID4gdGhpbmcgc2xvd2lu ZyB5b3UgZG93bi4KPiA+Cj4gSWYgeW91J3JlIHNlcmlvdXNseSBjb25zaWRlcmluZyB0aGF0LCB5 b3UgbWlnaHQgYWxzbyB3YW50IHRvIGJ1bXAgc3RydWN0IAo+IGRybV9jb2xvcl9sdXQgdG8gdXNl IDMyYml0cyBmaWVsZHMuCgpXaGljaCBpcyB3aGF0IEkgdGhvdWdodCB3ZSBoYWQgYWxyZWFkeSBh Z3JlZWQgdG8gZG8gd2hlbiB3ZSBzdGFydGVkCnBsYW5uaW5nIHRoaXMgY29sb3IgbWFuYWdlbWVu dCBzdHVmZi4gQnV0IEkgZ3Vlc3MgdGhhdCBwbGFuIGdvdApzb21laG93IHNjcmFwcGVkIGFmdGVy IEkgd2FzIG5vIGxvbmdlciBwYXJ0IG9mIHRoZSBkaXNjdXNzaW9ucy4KCj4gSXQgc2VlbXMgc29t ZSBwZW9wbGUgaGF2ZSBjb25jZXJuZWQgYWJvdXQgSERSLgoKSERSIGlzIGRlZmluaXRlbHkgc29t ZXRoaW5nIEknZCBsaWtlIHRvIGhhdmUgYSBsb29rIGF0LgoKLS0gClZpbGxlIFN5cmrDpGzDpApJ bnRlbCBPVEMKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18K ZHJpLWRldmVsIG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0 dHBzOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vZHJpLWRldmVsCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934554AbdBQPRV (ORCPT ); Fri, 17 Feb 2017 10:17:21 -0500 Received: from mga11.intel.com ([192.55.52.93]:33115 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934159AbdBQPRU (ORCPT ); Fri, 17 Feb 2017 10:17:20 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,172,1484035200"; d="scan'208";a="1130325698" Date: Fri, 17 Feb 2017 17:16:56 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Lionel Landwerlin Cc: Brian Starkey , Daniel Stone , Daniel Vetter , dri-devel , Linux Kernel Mailing List , Jani Nikula , Sean Paul Subject: Re: [PATCH v2] drm/color: Document CTM eqations Message-ID: <20170217151656.GV31595@intel.com> References: <20170131151828.GU31595@intel.com> <20170131153928.GB11506@e106950-lin.cambridge.arm.com> <20170131172215.GV31595@intel.com> <20170215113959.GT31595@intel.com> <20170217135451.GA18487@e106950-lin.cambridge.arm.com> <20170217145643.GU31595@intel.com> <492eec8f-a45e-190c-469f-018c82053f7f@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <492eec8f-a45e-190c-469f-018c82053f7f@intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 17, 2017 at 03:05:28PM +0000, Lionel Landwerlin wrote: > On 17/02/17 14:56, Ville Syrjälä wrote: > > On Fri, Feb 17, 2017 at 02:42:26PM +0000, Lionel Landwerlin wrote: > >> On 17/02/17 13:54, Brian Starkey wrote: > >>> What's the verdict? We've got [1] which is about to become another > >>> (driver) implementation - better to change before that merges than > >>> after I guess. > >>> > >>> -Brian > >>> > >>> [1] https://lkml.org/lkml/2017/2/13/304 > >>> > >>> On Wed, Feb 15, 2017 at 11:56:55AM +0000, Daniel Stone wrote: > >>>> Hi, > >>>> > >>>> On 15 February 2017 at 11:39, Ville Syrjälä > >>>> wrote: > >>>>> On Tue, Jan 31, 2017 at 06:46:39PM +0100, Daniel Vetter wrote: > >>>>>> On Tue, Jan 31, 2017 at 6:22 PM, Ville Syrjälä > >>>>>> wrote: > >>>>>>> Hmm. Two's complement is what I was thinking it is. Which shows that > >>>>>>> I never managed to read the code in any detail. Definitely needs to > >>>>>>> be documented properly. > >>>>>> That sounds supremely backwards. I guess we can't fix this anymore? > >>>>> I have no idea. Anyone else? > >>>> I don't know of any implementation using this; maybe closed Intel > >>>> Android stuff? Certainly GitHub showed no-one using it, and neither X > >>>> nor Weston/Mutter are using it yet. > >>>> > >>>> Cheers, > >>>> Daniel > >> If we're talking fixed point reprsentation, ChromeOS is using this : > >> > >> https://cs.chromium.org/chromium/src/ui/ozone/platform/drm/gpu/drm_device.cc?q=DrmDevice&l=209 > > So it's already using the sign+magnitude stuff. Which presumably > > means we can't change it to two's complement anymore :( Maybe we add a > > CTM2 property ;) > > > > Using sign+magnitude definitely looks rather inefficient since there's > > a branch inside the loop. With two's complement you wouldn't need that > > thing slowing you down. > > > If you're seriously considering that, you might also want to bump struct > drm_color_lut to use 32bits fields. Which is what I thought we had already agreed to do when we started planning this color management stuff. But I guess that plan got somehow scrapped after I was no longer part of the discussions. > It seems some people have concerned about HDR. HDR is definitely something I'd like to have a look at. -- Ville Syrjälä Intel OTC