From mboxrd@z Thu Jan 1 00:00:00 1970 From: Liviu Dudau Subject: Re: [PATCH 3/5] drm: convert drivers to use of_graph_get_remote_node Date: Mon, 6 Feb 2017 17:55:33 +0000 Message-ID: <20170206175533.GZ3140@e110455-lin.cambridge.arm.com> References: <20170204033635.10250-1-robh@kernel.org> <20170204033635.10250-4-robh@kernel.org> <20170206102933.GV3140@e110455-lin.cambridge.arm.com> <20170206170949.tmm4m2lm2rybm5dh@rob-hp-laptop> <20170206172306.GY3140@e110455-lin.cambridge.arm.com> <20170206173407.GK27312@n2100.armlinux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <20170206173407.GK27312-l+eeeJia6m9URfEZ8mYm6t73F7V6hmMc@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Russell King - ARM Linux Cc: Rob Herring , David Airlie , Daniel Vetter , Sean Paul , dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Frank Rowand , Boris Brezillon , Archit Taneja , Jingoo Han , Inki Dae , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , Kukjin Kim , Krzysztof Kozlowski , Javier Martinez Canillas , Stefan Agner , Alison Wang X List-Id: devicetree@vger.kernel.org On Mon, Feb 06, 2017 at 05:34:07PM +0000, Russell King - ARM Linux wrote: > On Mon, Feb 06, 2017 at 05:23:06PM +0000, Liviu Dudau wrote: > > On Mon, Feb 06, 2017 at 11:09:49AM -0600, Rob Herring wrote: > > > On Mon, Feb 06, 2017 at 10:29:33AM +0000, Liviu Dudau wrote: > > > > On Fri, Feb 03, 2017 at 09:36:33PM -0600, Rob Herring wrote: > > > > > - /* add the remote encoder port as component */ > > > > > - port = of_graph_get_remote_port_parent(ep); > > > > > - of_node_put(ep); > > > > > - if (!port || !of_device_is_available(port)) { > > > > > - of_node_put(port); > > > > > - return -EAGAIN; > > > > > > > > The HDLCD change looks reasonable except for this -EAGAIN business. I'll have to > > > > test your changes on my setup to see how this affects having the encoder as a module. > > > > > > What are you expecting to happen with -EAGAIN? This one was a bit of an > > > oddball. > > > > When both the HDLCD and the TDA998x drivers are compiled as modules, the > > order in which they are inserted can be somewhat random (due to testing). > > Not really "due to testing" but if you run a real distro, they tend to > have a multi-threaded behaviour when loading kernel modules at boot. Yeah, a lot of times I'm using a toy "distribution" (buildroot) as it boots faster under ARM models than a "real" (read systemd-based) distro would. > > > It is at that time when you want the probe of HDLCD to be retried on the > > insmod-ing of the tda998x.ko rather than fail entirely. > > -EAGAIN doesn't get you that, and in any case, solving that problem is > exactly why the component API exists - so that DRM only comes up once > all the necessary components are available. > > -EAGAIN also doesn't get you that from inside a probe function - such > an error will be reported in the kernel log, and no further action > will be taken (the device driver probe will be failed, and not > automatically retried. I stand corrected on the behaviour of the driver then. That was the original intent, to generate a re-probe of the driver. > > The only case that we automatically retry is if a driver returns > -EPROBE_DEFER. Everything else causes a probe failure. OK, I will fix the driver if Rob's patch still requires it. Best regards, Liviu > > -- > RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ > FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up > according to speedtest.net. -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html