From mboxrd@z Thu Jan 1 00:00:00 1970 From: khilman@deeprootsystems.com (Kevin Hilman) Date: Thu, 05 Aug 2010 08:12:04 -0700 Subject: [linux-pm] [PATCH/RFC] Runtime PM: ARM: subarch-specific extensions of pdev_archdata In-Reply-To: (Magnus Damm's message of "Thu, 5 Aug 2010 12:07:53 +0900") References: <1253670648-28610-1-git-send-email-khilman@deeprootsystems.com> <19129.63264.653666.70492@pilspetsen.it.uu.se> <4ABAAF1D.6090907@deeprootsystems.com> <87k4yhagv4.fsf@deeprootsystems.com> <34dc79dc-0868-4401-9fa5-c7134f6d4485@email.android.com> <87k4o7r7sv.fsf@deeprootsystems.com> Message-ID: <8739ut2iwr.fsf@deeprootsystems.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Magnus Damm writes: > On Thu, Aug 5, 2010 at 8:10 AM, Grant Likely wrote: >> On Tue, Aug 3, 2010 at 9:56 PM, Magnus Damm wrote: >>> On Wed, Aug 4, 2010 at 1:16 AM, Kevin Hilman >>> wrote: >>>> 2) custom vs. platform bus. >>>> >>>> The other issue under discussion between Grant & myself[1] has been the >>>> use of a custom bus instead of the platform bus. ?Following your lead, >>>> (and preferring that option) I continued to use the platform_bus since >>>> I only need to override a few of the dev_pm_ops functions. >>>> >>>> However, Grant is not happy about overriding the platform_bus. ?He would >>>> rather see each platform create a custom bus with it's own PM methods. >>>> >>>> In this thread[1], I did a quick and dirty proof of concept to show that >>>> it is possible, but quite frankly, I still much prefer continuing to use >>>> the platform_bus since it is mostly identical. >>>> >>>> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2010-June/018925.html >>> >>> Thanks for the pointer. I've been thinking of using a custom bus as >>> well, but from my point of view it's always looked like a lot of >>> coding without any clear benefit. I understand the idea of wanting to >>> use a single binary on a wide range of systems, and solving that seems >>> like a good plan. >>> >>> I'm not sure if a custom bus is the best idea. I wouldn't mind being >>> able to create platform bus instances though. >> >> The only problem with multiple platform_bus instances would be that >> drivers intended to work on both would need to be registered twice; >> once on the regular platform bus, and once on the custom bus. ?All the >> rest of the code would be shared, but it probably still doesn't >> reflect the model that you're shooting for. > > Do they really have to be registered twice? With the current driver > model yes, but perhaps it's possible to adjust the platform bus to > allow device<->driver matching across buses somehow. I would prefer to > register drivers only once. I would too. My primary objection to the custom bus approach is because I don't want drivers to have to care what bus (or SoC) they are connected to. Kevin