On 17/04/2015 17:49, Maxime Ripard wrote: > On Fri, Apr 17, 2015 at 05:01:55PM +0200, Gregory CLEMENT wrote: >> On 17/04/2015 16:50, Maxime Ripard wrote: >>> On Fri, Apr 17, 2015 at 04:40:43PM +0200, Gregory CLEMENT wrote: >>>> Hi Maxime, >>>> >>>> On 17/04/2015 16:32, Maxime Ripard wrote: >>>>> On Fri, Apr 17, 2015 at 04:19:22PM +0200, Boris Brezillon wrote: >>>>>> Hi Gregory, >>>>>> >>>>>> On Fri, 17 Apr 2015 15:01:01 +0200 >>>>>> Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx> wrote: >>>>>> >>>>>>> Hi Boris, >>>>>>> >>>>>>> On 17/04/2015 10:39, Boris Brezillon wrote: >>>>>>>> On Fri, 17 Apr 2015 10:33:56 +0200 >>>>>>>> Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx> wrote: >>>>>>>> >>>>>>>>> Hi Jason, >>>>>>>>> >>>>>>>>> On Mon, 13 Apr 2015 20:11:46 +0000 >>>>>>>>> Jason Cooper <jason@xxxxxxxxxxxxxx> wrote: >>>>>>>>> >>>>>>>>>>> >>>>>>>>>>>> I'd appreciate if we'd look into it. I understand from on-list and >>>>>>>>>>>> off-list discussion that the rewrite was unavoidable. So I'm willing to >>>>>>>>>>>> concede that. Giving people time to migrate from old to new while still >>>>>>>>>>>> being able to update for other security fixes seems reasonable. >>>>>>>>>>> >>>>>>>>>>> Jason, what do you think of the approach above? >>>>>>>>>> >>>>>>>>>> I say keep it simple. We shouldn't use the DT changes to trigger one >>>>>>>>>> vice the other. We need to be able to build both, but only load one at >>>>>>>>>> a time. If that's anything other than simple to do, then we make it a >>>>>>>>>> Kconfig binary choice and move on. >>>>>>>>> >>>>>>>>> Actually I was planning to handle it with a Kconfig dependency rule >>>>>>>>> (NEW_DRIVER depends on !OLD_DRIVER and OLD_DRIVER depends >>>>>>>>> on !NEW_DRIVER). >>>>>>>>> I don't know how to make it a runtime check without adding new >>>>>>>>> compatible strings for the kirkwood, dove and orion platforms, and I'm >>>>>>>>> sure sure this is a good idea. >>>>>>>> ^ not >>>>>>>> >>>>>>>>> Do you have any ideas ? >>>>>>> >>>>>>> You use devm_ioremap_resource() in the new driver, so if the old one >>>>>>> is already loaded the memory region will be already hold and the new >>>>>>> driver will simply fail during the probe. So for this part it is OK. >>>>>> >>>>>> I like the idea :-). >>>>> >>>>> Not really, how do you know which device is going to be probed? For >>>>> that matter, it's pretty much random, and you have no control over it. >>>>> >>>>> Why not just have a choice option, and select which one you want to >>>>> enable? >>>> >>>> Because you can't prevent an user to build a module, then modifying the >>>> configuration and building the other module. >>> >>> Well, actually, you don't even know if it's going to be a module. You >>> might very well have both drivers compiled statically in the kernel >>> image, and this is where the trouble begins. >> >> No it won't be possible, Boris already speak about this issue (see below): >> "Actually I was planning to handle it with a Kconfig dependency rule >> (NEW_DRIVER depends on !OLD_DRIVER and OLD_DRIVER depends >> on !NEW_DRIVER)." > > Which is a circular dependency and won't work. Indeed. Boris what about using choice/endchoice ? Thanks, Gregory > >>>> So even if there is a choice at build time, and I think that it is >>>> something expected for the v2, we still need preventing having the >>>> both drivers trying accessing the same hardware in the same time. >>> >>> Of course, but this is already there, and doesn't really address the >>> same issue. >> >> This was the only issue remaining, (see below again): >> "I don't know how to make it a runtime check ". And my last emails >> was bout it. > > Ok, my bad then :) > > Maxime > -- Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
