From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: broken nouveau dependency on power supply Date: Mon, 02 Apr 2012 13:53:23 +1000 Message-ID: <1333338803.30734.37.camel@pasglop> References: <1333328762.30734.24.camel@pasglop> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by gabe.freedesktop.org (Postfix) with ESMTP id ACBD09E70A for ; Sun, 1 Apr 2012 20:53:42 -0700 (PDT) In-Reply-To: <1333328762.30734.24.camel@pasglop> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org Errors-To: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org To: linux-kernel@vger.kernel.org Cc: Anton Vorontsov , Linus Torvalds , Woodhouse , dri-devel@lists.freedesktop.org, David@freedesktop.org List-Id: dri-devel@lists.freedesktop.org On Mon, 2012-04-02 at 11:06 +1000, Benjamin Herrenschmidt wrote: > Hi folks ! > > With CONFIG_POWER_SUPPLY=m & nouveau built-in we get a build failure: > > drivers/built-in.o: In function `.nouveau_pm_trigger': > (.text+0xa56e8): undefined reference to `.power_supply_is_system_supplied' > > nouveau probably needs to depends on CONFIG_POWER_SUPPLY to force a module > build with the latter is =m Ok, not that trivial... The problem is more like POWER_SUPPLY should be a bool, not a tristate. If you think about it: you don't want things like nouveau to depend on a random subsystem like that, people will never get it. In fact, POWER_SUPPLY provides empty inline stubs when not enabled, so that's really designed to not have depends... However that -cannot- work if POWER_SUPPLY is modular and the drivers who use it are not. The only fixes here that make sense I can think of that don't also involve Kconfig horrors are: - Ugly: in power_supply.h, use the extern variant if defined(CONFIG_POWER_SUPPLY) || (defined(CONFIG_POWER_SUPPLY_MODULE) && defined(MODULE)) IE. use the stub if power supply is a module and what is being built is built-in. Of course that's not only ugly, it somewhat sucks from a user perspective as the subsystem now exists but can't be used by some drivers... - Better: Just make the bloody thing a bool :-) The power supply framework itself is small enough, just make it a boolean option and avoid the problem entirely. The actual power supply sub drivers can remain modular of course. Cheers, Ben.