From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rhyland Klein Subject: Re: [RFC v2 2/3] power: power_supply: Add core support for supplied_nodes Date: Fri, 22 Feb 2013 16:55:42 -0500 Message-ID: <5127E95E.4010500@nvidia.com> References: <1361488272-21010-1-git-send-email-rklein@nvidia.com> <1361488272-21010-3-git-send-email-rklein@nvidia.com> <5127CBD9.9050501@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5127CBD9.9050501-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephen Warren Cc: Anton Vorontsov , David Woodhouse , Grant Likely , Rob Herring , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org On 2/22/2013 2:49 PM, Stephen Warren wrote: > On 02/21/2013 04:11 PM, Rhyland Klein wrote: >> With the growing support for dt, it make sense to try to make use of >> dt features to make the general code cleaner. This patch is an >> attempt to commonize how chargers and their supplies are linked. >> >> Following common dt convention, the "supplied-to" char** list is >> replaced with phandle lists defined in the supplies which contain >> phandles of their suppliers. >> >> This has the effect however of introducing an inversion in the internal >> mechanics of how this information is stored. In the case of non-dt, >> the char** list of supplies is stored in the charger. In the dt case, >> a device_node * list is stored in the supplies of their chargers, >> however this seems to be the only way to support this. > When parsing the DT, you can convert from phandle (or struct device_node > *) to the name of the referenced supply by simple lookup. So, you could > store supply names rather than device_node *. Can't you then also fill > in the referenced supply's existing char** list of supplies? > > Of course, making this interact-with/use -EPROBE_DEFERRED might be > challenging, since this would be operating in the inverse order to other > producer/consumer relationships, which might cause loops. The main problem I ran into when I was essentially trying to do this, was that the list of names that are used to match the power_supplies are the strings set as "name" in the power_supply structs. This doesn't get set automatically based on their nodes, and it is currently up to each driver to define their own name. For example, the sbs-battery driver uses the name "sbs-XXX" where XX is its dev_name. Other drivers use "%s-$%d" as i2c_device_id->name, + instance number. Then the only solution I see is to require a new property that defines the power-supply's name in the devicetree. This solution with device_nodes, while not ideal, seems the be the best bet from what I see. Maybe someone else has a better idea. -rhyland -- nvpublic