From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: Caching of EDID for X server to decrease startup time of X server Date: Mon, 10 Aug 2015 15:36:13 +0200 Message-ID: <20150810133612.GD7302@ulmo.nvidia.com> References: <1439065137.6974.23.camel@users.sourceforge.net> <20150810130148.GE1262@ulmo.nvidia.com> <20150810131342.GJ11040@nuc-i3427.alporthouse.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============2107755336==" Return-path: Received: from mail-pa0-f51.google.com (mail-pa0-f51.google.com [209.85.220.51]) by gabe.freedesktop.org (Postfix) with ESMTPS id C644C6E013 for ; Mon, 10 Aug 2015 06:37:03 -0700 (PDT) Received: by pacgr6 with SMTP id gr6so27437163pac.2 for ; Mon, 10 Aug 2015 06:37:03 -0700 (PDT) In-Reply-To: <20150810131342.GJ11040@nuc-i3427.alporthouse.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Chris Wilson , Paul Menzel , Russell King - ARM Linux , dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org --===============2107755336== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="sgneBHv3152wZ8jf" Content-Disposition: inline --sgneBHv3152wZ8jf Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Aug 10, 2015 at 02:13:43PM +0100, Chris Wilson wrote: > On Mon, Aug 10, 2015 at 03:01:49PM +0200, Thierry Reding wrote: > > Russell and Sascha were discussing this kind of caching in the i.MX > > driver recently. Adding both for visibility. Also not trimming the quote > > in case they don't have the original. > >=20 > > It sounds like this could be useful to have in the core. As I understand > > it, hotplug detection is pretty well specified for more modern display > > interfaces (like HDMI and DisplayPort), so I think caching of this sort > > could work for those. However, I think some older interfaces such as VGA > > (or perhaps even DVI as well) don't have reliable hotplug detection and > > hence would need to be able to force reading the EDID. > >=20 > > Still, perhaps a connector flag could be introduced to enable caching on > > a per-connector basis, and then we should be able to deal with this in > > the DRM core, rather than have per-driver quirks. >=20 > We've shied away from EDID caching precisely because HPD on Intel is > notoriously unreliable. The last suggestion no one followed up with was > a short term EDID cache. That's why I think a per-connector flag would be good. It would allow this caching to be enabled only where it's been confirmed to be safe. I'd expect that HPD works well for HDMI and DisplayPort even on Intel. Thierry --sgneBHv3152wZ8jf Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJVyKjMAAoJEN0jrNd/PrOhWvQP/A62fTd+LSxpHD7Dl09p3Z9x //+XNAJIPwPeAnANe1Nm181OSKh/1pt1XWQh2x178Zje36JaI3xJEs4+RNFVOwHn EszFkNFK8bkSGx0wGYlUxUtwHYObuUH/kTpGRt1reg/cGeGiIxwCW9IUZqdfol1Z jcWuzGf46k4LiTxFOSsJ0hDsqYD/iGCh8ryK0dXW7LSUcLn3ookhnw1MA7hm3Hjp Sra6RLBVt/EGSGI0BBIUA9xcp4MfHBE2/eMpf+RdLfAUK7ubUs8/RUMA8R/Ro0d4 87e/qFuiRSawJ+9T5a23GrRSuNbVq91fqP8UEPlhnBRoqpcHvotCQnvWe4HySsJd aKIRppG41NAr41RJSyeqLls6DnImvA8R7Vh5Y/SaCBlt+eftEJP7/ZPBIl0rwkqR b7ij6iUSvX49/HAdIAD8pJESP1VZ8cYhDU89DYozT3/dkvNZGqfx8I/Cr5YOr7A+ F+sgwrfsyzhKIahRLl1BAizrgoXfqdtMBS9ektkKhB7sWUXqdAtFy8jF32qEfxEo WnhT9bXEiS8Q8vdx8oRTk0U/810gsqjrmD/HojQZAWQCVVkrLmnB5b00reIF7KsD sqN3pM2eqvalaCRCGHGo2yfRnCD9jIF+58XR0rJlwCI1/v2/AmZkqs54V2G/cDA5 wHAEtmzpQ/Dxki9Gm+S4 =ObX1 -----END PGP SIGNATURE----- --sgneBHv3152wZ8jf-- --===============2107755336== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KZHJpLWRldmVs IG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHA6Ly9saXN0 cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9kcmktZGV2ZWwK --===============2107755336==--