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)." > >> 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. Gregory > > 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
