From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adam Jackson Subject: Re: Valid DP connection without EDID? Date: Mon, 17 Sep 2012 12:24:36 -0400 Message-ID: <1347899076.25266.46.camel@atropine> References: <50534C4F.6020607@redhat.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0234699114==" Return-path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by gabe.freedesktop.org (Postfix) with ESMTP id BCFA59E798 for ; Mon, 17 Sep 2012 09:24:40 -0700 (PDT) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Takashi Iwai Cc: mmarek@suse.cz, intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org --===============0234699114== Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-ujXz3EIH476Uxezlld3b" --=-ujXz3EIH476Uxezlld3b Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2012-09-17 at 11:32 +0200, Takashi Iwai wrote: > At Mon, 17 Sep 2012 19:11:34 +1000, > Dave Airlie wrote: > > On Mon, Sep 17, 2012 at 6:28 PM, Takashi Iwai wrote: > > > At Mon, 17 Sep 2012 18:21:47 +1000, > > > Dave Airlie wrote: > > >> On Mon, Sep 17, 2012 at 6:16 PM, Takashi Iwai wrote: > > >> > At Fri, 14 Sep 2012 11:25:03 -0400, > > >> > Adam Jackson wrote: > > >> >> > > >> >> Can you be more specific here? What DPCD does it return? > > >> > > > >> > It shows "DPCD: 110a820100030181" So dpcd[0x5] is 0x03, and drm_dp_helper.h says: #define DP_DOWNSTREAMPORT_PRESENT 0x005 # define DP_DWN_STRM_PORT_PRESENT (1 << 0) # define DP_DWN_STRM_PORT_TYPE_MASK 0x06 /* 00b =3D DisplayPort */ /* 01b =3D Analog */ /* 10b =3D TMDS or HDMI */ /* 11b =3D Other */ # define DP_FORMAT_CONVERSION (1 << 3) So there we go, it's a branch device with VGA downstream of it. We need to figure out the connectivity of the downstream port. > > > Checking DPCD bits might work, but I have no exact spec of DPCD, so n= o > > > idea whether the above is really wrong or not. > >=20 > > Is there a VGA port on the docking station, it might have a DP->VGA in > > it, or dual-link DVI port. >=20 > Ah, right, that's the missing piece! >=20 > It's a DP->VGA conversion indeed. Plugging to a VGA connector appears > as DP2. Oh well, I didn't think of this possibility at all. >=20 > But then this makes me wonder how to solve the problem at best. > It's obviously a bogus connection status returned from the driver. > DP2 advertises itself as if connected. I wouldn't quite say it's bogus, more that we're describing the connection status of "the nearest DP device" as if it were the connection status of the whole wire. I started a patch series for this a bit ago, I'll send it on momentarily. - ajax --=-ujXz3EIH476Uxezlld3b Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEABECAAYFAlBXTsUACgkQW4otUKDs0NMsjACfTwojSkcKZxCRgeIEO9XhmV6e 30UAoOPqGIErjLmbeI7GKgi43ASYCYyV =lr+q -----END PGP SIGNATURE----- --=-ujXz3EIH476Uxezlld3b-- --===============0234699114== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx --===============0234699114==--