From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: [PATCH 07/14] media: soc-camera: support deferred probing of clients Date: Wed, 10 Apr 2013 14:56:27 +0100 Message-ID: <20130410135627.GD9243@opensource.wolfsonmicro.com> References: <1348754853-28619-1-git-send-email-g.liakhovetski@gmx.de> <1348754853-28619-8-git-send-email-g.liakhovetski@gmx.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Dnvf+KcI+0MByPWJ" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-sh-owner@vger.kernel.org To: Barry Song <21cnbao@gmail.com> Cc: Guennadi Liakhovetski , Sylwester Nawrocki , linux-media@vger.kernel.org, linux-sh@vger.kernel.org, devicetree-discuss@lists.ozlabs.org, Magnus Damm , Hans Verkuil , Laurent Pinchart , "renwei.wu" , DL-SHA-WorkGroupLinux , xiaomeng.hou@csr.com, zilong.wu@csr.com List-Id: devicetree@vger.kernel.org --Dnvf+KcI+0MByPWJ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Apr 10, 2013 at 09:53:20PM +0800, Barry Song wrote: > 2013/4/10 Guennadi Liakhovetski : > >> what about another possible way: > >> we let all host and i2c client driver probed in any order, > > This cannot work, because some I2C devices, e.g. sensors, need a clock > > signal from the camera interface to probe. Before the bridge driver has > > completed its probing and registered a suitable clock source with the > > v4l2-clk framework, sensors cannot be probed. And no, we don't want to > > fake successful probing without actually being able to talk to the > > hardware. > i'd say same dependency also exists on ASoC. a "fake" successful > probing doesn't mean it should really begin to work if there is no > external trigger source. ASoC has successfully done that by a machine > driver to connect all DAI. > a way is we put all things ready in their places, finally we connect > them together and launch the whole hardware flow. In the ASoC case the idea is that drivers should probe as far as they can with just the chip and then register with the core. The machine driver defers probing until all components have probed and then runs through second stage initialisaton which pulls everything together. --Dnvf+KcI+0MByPWJ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJRZW+AAAoJELSic+t+oim9RisP/0JnIg+nLUD6ybwBMA2Mc1d+ GvVQVmasJue54gyGd9X+XcRXdBrtSw8UUiSI5rUFoOHIyc6ZLYz+qprpSCjIEAUz BRiPG2zwpEsHvdI9ys3mCtwU/9Go4pnxhGUHLtb7xHbsORxdaTyN0yiiOEwbwaAe 9mfzBn3iZGru5vjSf7vIft/YX5rcmsMaRq9typ1b10Q1dEHJQFk3V4GVN1KbpULG 4xEOaipv3HorsJhcEuc7r+LIXp7Zp9Yg2W5RVTTu7CDnGWmyu4ELSCDa8mWsqAdu 80N2zDzQQHu+QZwxrGp2GPHRbBeL4Pekp3GHUXqUokWnHSHe1pTaqEvp4BpBMRUn UQqDJkFNNu8n3bL9UjQ7feVgo1obX4e9B1BG4Z+PWFbIViK/Q9mMU5EatSesx7Ju qqCIIGKG0Q8YxildXDf9y70CirkXIDyvOt42O0uxZTeQMMx5AdP0y/gvz+nPfdVw kReb2sXLVKvysXmvsG5B8L0FnWKB1sDDMCDCrkZowzIDkuhFZ9ZphdeUr9j/IKf7 MjnfIGrsGos7+D/yVXBJJJ/t2JZ1IzGzNdoGhG/XYLS1hjmhj5KiBFd2k3Mr77/u Qa+pG7guhaCYlh+8/CcCCpabjW6wPQfjtzZ1bMjAx77grcm+jGlSJJHMdIdOd7nD N+AOg+yeJVJQwvabeOMk =XoTj -----END PGP SIGNATURE----- --Dnvf+KcI+0MByPWJ--