From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= Subject: Re: [PATCH] drm: fourcc byteorder: brings header file comments in line with reality. Date: Fri, 12 May 2017 12:10:22 +0300 Message-ID: <20170512091022.GM12629@intel.com> References: <20170421075825.6307-1-kraxel@redhat.com> <20170421092530.GE30290@intel.com> <1492768218.25675.33.camel@redhat.com> <20170421110804.GH30290@intel.com> <20170511212311.GA6780@amd> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: <20170511212311.GA6780@amd> List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org Sender: "amd-gfx" To: Pavel Machek Cc: Jani Nikula , amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, David Airlie , Michel =?iso-8859-1?Q?D=E4nzer?= , open list , dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, Pekka Paalanen , Sean Paul , Gerd Hoffmann , Alex Deucher , Daniel Vetter , Ilia Mirkin T24gVGh1LCBNYXkgMTEsIDIwMTcgYXQgMTE6MjM6MTFQTSArMDIwMCwgUGF2ZWwgTWFjaGVrIHdy b3RlOgo+IE9uIEZyaSAyMDE3LTA0LTIxIDE0OjA4OjA0LCBWaWxsZSBTeXJqw6Rsw6Qgd3JvdGU6 Cj4gPiBPbiBGcmksIEFwciAyMSwgMjAxNyBhdCAxMTo1MDoxOEFNICswMjAwLCBHZXJkIEhvZmZt YW5uIHdyb3RlOgo+ID4gPiBPbiBGciwgMjAxNy0wNC0yMSBhdCAxMjoyNSArMDMwMCwgVmlsbGUg U3lyasOkbMOkIHdyb3RlOgo+ID4gPiA+IE9uIEZyaSwgQXByIDIxLCAyMDE3IGF0IDA5OjU4OjI0 QU0gKzAyMDAsIEdlcmQgSG9mZm1hbm4gd3JvdGU6Cj4gPiA+ID4gPiBXaGlsZSB3b3JraW5nIG9u IGdyYXBoaWNzIHN1cHBvcnQgZm9yIHZpcnR1YWwgbWFjaGluZXMgb24gcHBjNjQgKHdoaWNoCj4g PiA+ID4gPiBleGlzdHMgaW4gYm90aCBsaXR0bGUgYW5kIGJpZyBlbmRpYW4gdmFyaWFudHMpIEkn dmUgZmlndXJlZCB0aGUgY29tbWVudHMKPiA+ID4gPiA+IGZvciB2YXJpb3VzIGRybSBmb3VyY2Mg Zm9ybWF0cyBpbiB0aGUgaGVhZGVyIGZpbGUgZG9uJ3QgbWF0Y2ggcmVhbGl0eS4KPiA+ID4gPiA+ IAo+ID4gPiA+ID4gQ29tbWVudHMgc2F5cyB0aGUgUkdCIGZvcm1hdHMgYXJlIGxpdHRsZSBlbmRp YW4sIGJ1dCBpbiBwcmFjdGljZSB0aGV5Cj4gPiA+ID4gPiBhcmUgbmF0aXZlIGVuZGlhbi4gIExv b2sgYXQgdGhlIGRybV9tb2RlX2xlZ2FjeV9mYl9mb3JtYXQoKSBoZWxwZXIuICBJdAo+ID4gPiA+ ID4gbWFwcyAtLSBmb3IgZXhhbXBsZSAtLSBicHAvZGVwdGggMzIvMjQgdG8gRFJNX0ZPUk1BVF9Y UkdCODg4OCwgbm8gbWF0dGVyCj4gPiA+ID4gPiB3aGVuZXZlciB0aGUgbWFjaGluZSBpcyBsaXR0 bGUgZW5kaWFuIG9yIGJpZyBlbmRpYW4uICBUaGUgdXNlcnMgb2YgdGhpcwo+ID4gPiA+ID4gZnVu Y3Rpb24gKGZiZGV2IGVtdWxhdGlvbiwgRFJNX0lPQ1RMX01PREVfQURERkIpIGV4cGVjdCB0aGUg ZnJhbWVidWZmZXIKPiA+ID4gPiA+IGlzIG5hdGl2ZSBlbmRpYW4sIG5vdCBsaXR0bGUgZW5kaWFu LiAgTW9zdCB1c2Vyc3BhY2UgYWxzbyBvcGVyYXRlcyBvbgo+ID4gPiA+ID4gbmF0aXZlIGVuZGlh biBvbmx5Lgo+ID4gPiA+IAo+ID4gPiA+IEknbSBub3QgYSBmYW4gb2YgIm5hdGl2ZSIuIE5hdGl2 ZSB0byB3aGF0PyAiQ1BVIiBvciAiaG9zdCIgaXMgd2hhdCBJJ2QKPiA+ID4gPiBjYWxsIGl0Lgo+ ID4gPiAKPiA+ID4gbmF0aXZlID09IHdoYXRldmVyIHRoZSBjcHUgaXMgdXNpbmcuCj4gPiA+IAo+ ID4gPiBJIHBlcnNvbmFsbHkgZmluZCAibmF0aXZlIiBtb3JlIGludHVpdGl2ZSwgYnV0IGF0IHRo ZSBlbmQgb2YgdGhlIGRheSBJCj4gPiA+IGRvbid0IG1pbmQgbXVjaC4gIElmIHBlb3BsZSBwcmVm ZXIgImhvc3QiIG92ZXIgIm5hdGl2ZSIgSSdsbCBjaGFuZ2UgaXQuCj4gPiAKPiA+ICJuYXRpdmUi IHRvIG1lIGZlZWxzIG1vcmUgbGlrZSAibmF0aXZlIHRvIHRoZSBHUFUiIHNpbmNlIHRoZXNlIHRo aW5ncwo+ID4gcmVhbGx5IGFyZSB0aWVkIHRvIHRoZSBHUFUgbm90IHRoZSBDUFUuIFRoYXQncyBh bHNvIHdoeSBJIHdlbnQgd2l0aCB0aGUKPiA+IGV4cGxpY2l0IGVuZGlhbm5lc3Mgb3JpZ2luYWxs eSBzbyB0aGF0IHRoZSBkcml2ZXIgY291bGQgcHJvcGVybHkgZGVjbGFyZQo+ID4gd2hhdCB0aGUg R1BVIHN1cHBvcnRzLgo+IAo+IFlvdSBjYW4gZWFzaWx5IGhhdmUgbW9yZSB0aGFuIG9uZSBHUFUg aW4gdGhlIHN5c3RlbS4gUGx1cyB0aGVzZSBhcmUKPiB1c2VkIGJ5IGNhbWVyYXMgLyBmcmFtZSBn cmFiYmVycywgdG9vLiBTbyBhbnl0aGluZyBlbHNlIHRoYW4gQ1BVCj4gZW5kaWFubmVzcyBpcyBi YWRseSBkZWZpbmVkLgoKVGhlIGZyYW1lYnVmZmVyIGhhcyB2ZXJ5IGxpdHRsZSB0byBkbyB3aXRo IHRoZSBDUFUuIFRoZSBkaXNwbGF5CmNvbnRyb2xsZXIgaXMgdGhlIG9ubHkgY29uc3VtZXIsIGFu ZCB0aGUgcHJvZHVjZXIgY291bGQgYmUKd2hhdGV2ZXIuCgotLSAKVmlsbGUgU3lyasOkbMOkCklu dGVsIE9UQwpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwph bWQtZ2Z4IG1haWxpbmcgbGlzdAphbWQtZ2Z4QGxpc3RzLmZyZWVkZXNrdG9wLm9yZwpodHRwczov L2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2FtZC1nZngK From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932798AbdELJKn (ORCPT ); Fri, 12 May 2017 05:10:43 -0400 Received: from mga02.intel.com ([134.134.136.20]:7358 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932283AbdELJK3 (ORCPT ); Fri, 12 May 2017 05:10:29 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.38,328,1491289200"; d="scan'208";a="1146979405" Date: Fri, 12 May 2017 12:10:22 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Pavel Machek Cc: Gerd Hoffmann , dri-devel@lists.freedesktop.org, Daniel Vetter , Pekka Paalanen , Ilia Mirkin , Michel =?iso-8859-1?Q?D=E4nzer?= , Alex Deucher , amd-gfx@lists.freedesktop.org, Jani Nikula , Sean Paul , David Airlie , open list Subject: Re: [PATCH] drm: fourcc byteorder: brings header file comments in line with reality. Message-ID: <20170512091022.GM12629@intel.com> References: <20170421075825.6307-1-kraxel@redhat.com> <20170421092530.GE30290@intel.com> <1492768218.25675.33.camel@redhat.com> <20170421110804.GH30290@intel.com> <20170511212311.GA6780@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170511212311.GA6780@amd> 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 Thu, May 11, 2017 at 11:23:11PM +0200, Pavel Machek wrote: > On Fri 2017-04-21 14:08:04, Ville Syrjälä wrote: > > On Fri, Apr 21, 2017 at 11:50:18AM +0200, Gerd Hoffmann wrote: > > > On Fr, 2017-04-21 at 12:25 +0300, Ville Syrjälä wrote: > > > > On Fri, Apr 21, 2017 at 09:58:24AM +0200, Gerd Hoffmann wrote: > > > > > While working on graphics support for virtual machines on ppc64 (which > > > > > exists in both little and big endian variants) I've figured the comments > > > > > for various drm fourcc formats in the header file don't match reality. > > > > > > > > > > Comments says the RGB formats are little endian, but in practice they > > > > > are native endian. Look at the drm_mode_legacy_fb_format() helper. It > > > > > maps -- for example -- bpp/depth 32/24 to DRM_FORMAT_XRGB8888, no matter > > > > > whenever the machine is little endian or big endian. The users of this > > > > > function (fbdev emulation, DRM_IOCTL_MODE_ADDFB) expect the framebuffer > > > > > is native endian, not little endian. Most userspace also operates on > > > > > native endian only. > > > > > > > > I'm not a fan of "native". Native to what? "CPU" or "host" is what I'd > > > > call it. > > > > > > native == whatever the cpu is using. > > > > > > I personally find "native" more intuitive, but at the end of the day I > > > don't mind much. If people prefer "host" over "native" I'll change it. > > > > "native" to me feels more like "native to the GPU" since these things > > really are tied to the GPU not the CPU. That's also why I went with the > > explicit endianness originally so that the driver could properly declare > > what the GPU supports. > > You can easily have more than one GPU in the system. Plus these are > used by cameras / frame grabbers, too. So anything else than CPU > endianness is badly defined. The framebuffer has very little to do with the CPU. The display controller is the only consumer, and the producer could be whatever. -- Ville Syrjälä Intel OTC