From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Anholt Subject: Re: [RFC PATCH 0/3] drm/panel: Support panel detection Date: Mon, 30 Apr 2018 10:22:19 -0700 Message-ID: <87d0ygzk1g.fsf@anholt.net> References: <20180430144323.9233-1-boris.brezillon@bootlin.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1270767918==" Return-path: Received: from anholt.net (anholt.net [50.246.234.109]) by gabe.freedesktop.org (Postfix) with ESMTP id 33FF9899D4 for ; Mon, 30 Apr 2018 17:22:25 +0000 (UTC) In-Reply-To: <20180430144323.9233-1-boris.brezillon@bootlin.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Thierry Reding , dri-devel@lists.freedesktop.org Cc: David Airlie , Boris Brezillon List-Id: dri-devel@lists.freedesktop.org --===============1270767918== Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" --=-=-= Content-Type: text/plain Boris Brezillon writes: > Some panels are connected through extension boards an provide an easy > way for the main board to detect when they are present (like checking > for a working I2C communication with a device and making sure a > specific reg in this device has a consistent value). > > When this is the case, we might want to support dynamic panel detection > and only expose the display (and its display modes) when the panel is > detected, similar to the monitor detection we use for regular > connectors (HDMI, DVI, ...). > > This solves a problem we have on the Rpi when the panel is not > connected to the board but described in the DT. This prevents the whole > display pipeline from being exposed because one of the element (the > panel) is missing. > > This was posted as an RFC because I'm not sure dynamically detecting > panels or supporting panel hotplug is actually something we want to do. I want to clarify here: we're not trying to do panel hotplug. We're trying to boot-time-only detection of whether or not the standard panel is plugged in. Since this is something like the 6th variation of trying to get this driver to work whether or not the panel is plugged in at boot, I'm leaning toward just asking the closed source firmware to hack the DT to add/remove the panel's node depending on whether it can probe it on I2C. Relying on more closed source software in order to work around something so trivial is really frustrating, though. --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE/JuuFDWp9/ZkuCBXtdYpNtH8nugFAlrnUMsACgkQtdYpNtH8 nugB5A//VydYFeUCV/mKK7JzsLuaYiSjyK36iY+YHPFda4bnpZlMvqPdYWe/viHn t/RBpYcxBnHwSRhOkfqKgrZZagkiJzR3r4NsBgzqDZIgKNd50b8satXwFuBPyjVO woO1NxtNBmN1ZJaag4LT1e9iagBIszyuytythCJCvd6e2yZP3yrz57bL6Yj/h7jm BJ9GX3C34iLpP8AlRWQTqqMfdjHLwAabkHXjS+jzNIP190QHP2qk1vBMbzwWjfAP F4XOXHFUaTqtQIKdWnuRHbNuCa3opK9xFJ/svHHNqBxhGC9/p2jyn0L1kjx1SNbW XzKMBqrBfnX+InV0tMv/H/wB7vj4bYE09am26xvDeT7gU+SChoI8acouQtrdGMNt fvzUIcXAHjnN0ONWCxJ84DS+mEQPuwqfzLbqO2UXUwAHsjVSp/AIuY8Sg1H3CDEv sxpt/6ZG6hpGLstDbKzSx1U/WiCGLeQPgNJ1BNNzu7SulBO6HlZKDMjv29uJhwYF 7oLx4b2SbmXzurJgRbHWmER7qGJ5za5qFuglgV0YI3q/mJJhpn1nKU8q615kO7nI SKz+dsX8XY3EU719MvAPneveqsoddpU20y1XemA2wuDQRWeg4R9RPdlbs7ntbigi ykopGcp+NFbS4/rrqoJWmrX2pwg/y9SNj0JhofllMJGgJjtr4IY= =jlKk -----END PGP SIGNATURE----- --=-=-=-- --===============1270767918== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KZHJpLWRldmVs IG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlz dHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vZHJpLWRldmVsCg== --===============1270767918==--