From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Anholt Subject: Re: [PATCH] drm/vc4: Ignore alpha on primary plane Date: Fri, 02 Mar 2018 09:13:14 -0800 Message-ID: <87371i8kph.fsf@anholt.net> References: <1519950760-68447-1-git-send-email-stschake@gmail.com> <20180302143922.GL5453@intel.com> <20180302144352.GM5453@intel.com> <20180302152117.GN5453@intel.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1680141539==" Return-path: Received: from anholt.net (anholt.net [50.246.234.109]) by gabe.freedesktop.org (Postfix) with ESMTP id 7FC7C6E1F2 for ; Fri, 2 Mar 2018 17:13:17 +0000 (UTC) In-Reply-To: <20180302152117.GN5453@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Ville =?utf-8?B?U3lyasOkbMOk?= , Stefan Schake Cc: David Airlie , linux-rpi-kernel@lists.infradead.org, dri-devel List-Id: dri-devel@lists.freedesktop.org --===============1680141539== Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" --=-=-= Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Ville Syrj=C3=A4l=C3=A4 writes: > On Fri, Mar 02, 2018 at 04:06:58PM +0100, Stefan Schake wrote: >> Hey Ville, >>=20 >> On Fri, Mar 2, 2018 at 3:43 PM, Ville Syrj=C3=A4l=C3=A4 >> wrote: >> > On Fri, Mar 02, 2018 at 04:39:22PM +0200, Ville Syrj=C3=A4l=C3=A4 wrot= e: >> >> If you want the plane to always be opaque you shouldn't expose any >> >> formats with alpha. >> >> >> >> Also what happens if one disables the primary plane? Or does the driv= er >> >> not allow that? >> > >> > Or just makes the plane not cover the entire screen? >>=20 >> We've exposed alpha formats in the past so disabling that now would break >> userspace, certainly Android that chooses alpha-everything. > > So it refuses to even run on hardware that can't do per-pixel alpha on > the primary plane? > >> The VC4 HVS >> has no fixed planes so I'll acknowledge that the concept of a primary pl= ane >> is somewhat dubious and userspace could disable it or make it not cover = the >> entire screen, making this ineffective. >>=20 >> But then ultimately there doesn't seem to be a standard for what the dis= play >> is supposed to be if you have transparent pixels with no plane to blend = to >> below. > > The standard is black. IMO it's a driver bug if it fails to do that. If the plane is premultiplied (isn't that what DRM planes are supposed to be? I can't find any docs), then blending against black is the same as not doing any blending at all. --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE/JuuFDWp9/ZkuCBXtdYpNtH8nugFAlqZhisACgkQtdYpNtH8 nuiH5Q/+NbpfQGO/d3dTwTUBJMuWa5mVUhyCkjjGqnshSo6+rS7x6RPjlfhAYoeR Rlc7xL4pqOjtcEgwnCsEP7gNLned0vQKBHVY1WCD6SENqetCbio4uakuHbqXbh8J Wx/px0nVbA+nUjipxIziV1SDm39IKeEs+RG/FJhib8Xt0tXjejVWRbjgVYIhO08Y U+h3Rx+3YcO1PW0eV3slIgAvgcOKi7JjP5fzkLk6MlfcYkar5OURecgOX5AnR18H 39VaH9v2NM9aXFTsSbKGJT+tmtB4RXR5Ok1ChUt9EUvOMasNlliigQAZ1DzDChOe 2N6s6PeBFCmzbOs36eZdrUqjcFEoWam4/gBdmwsbaL0HG8ol5VlEOFtPQ+2SnJXR Oi0xfSX9GE+Q71tmmcbH26Ykd/03W/DdSHgnqK9//iqszORJaq/OleZ6EpgY451w rcXKPo1pQvWsnjBeliESrSwLY87YkkdFSMk50zbvo7Qp0v946BrZmP/kfevjdrk5 yf+nyCwpWnIkOtj40oUp2MEq3a6xhZInf4XY0VngGZY1Ax67K3QNiKRDY+mJPgiN ukCgqPeUjHxjGudEbIMgfM5hFfYk+SJgInnS/hBSeLh+Y36TFWoc2cDDext6Judr do4JztPfSASGY9mZojs5vL2RQB2rqIj5Xq+QXwoi1UQL3R5KZFg= =g2+r -----END PGP SIGNATURE----- --=-=-=-- --===============1680141539== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KZHJpLWRldmVs IG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlz dHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vZHJpLWRldmVsCg== --===============1680141539==--