On 26 September 2015 at 21:22, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Sat, Sep 26, 2015 at 01:17:04PM -0500, Rob Herring wrote: >> On 09/21/2015 09:02 AM, Tomeu Vizoso wrote: >> > Hello, >> > >> > I have a problem with the panel on my Tegra Chromebook taking longer >> > than expected to be ready during boot (Stéphane Marchesin reported what >> > is basically the same issue in [0]), and have looked into ordered >> > probing as a better way of solving this than moving nodes around in the >> > DT or playing with initcall levels and linking order. >> > >> > While reading the thread [1] that Alexander Holler started with his >> > series to make probing order deterministic, it occurred to me that it >> > should be possible to achieve the same by probing devices as they are >> > referenced by other devices. >> > >> > This basically reuses the information that is already implicit in the >> > probe() implementations, saving us from refactoring existing drivers or >> > adding information to DTBs. >> > >> > During review of v1 of this series Linus Walleij suggested that it >> > should be the device driver core to make sure that dependencies are >> > ready before probing a device. I gave this idea a try [2] but Mark Brown >> > pointed out to the logic duplication between the resource acquisition >> > and dependency discovery code paths (though I think it's fairly minor). >> > >> > To address that code duplication I experimented with Arnd's devm_probe >> > [3] concept of having drivers declare their dependencies instead of >> > acquiring them during probe, and while it worked [4], I don't think we >> > end up winning anything when compared to just probing devices on-demand >> > from resource getters. >> > >> > One remaining objection is to the "sprinkling" of calls to >> > of_device_probe() in the resource getters of each subsystem, but I think >> > it's the right thing to do given that the storage of resources is >> > currently subsystem-specific. >> > >> > We could avoid the above by moving resource storage into the core, but I >> > don't think there's a compelling case for that. >> > >> > I have tested this on boards with Tegra, iMX.6, Exynos, Rockchip and >> > OMAP SoCs, and these patches were enough to eliminate all the deferred >> > probes (except one in PandaBoard because omap_dma_system doesn't have a >> > firmware node as of yet). >> > >> > Have submitted a branch [5][6][7] with these patches on top of today's >> > linux-next (20150921) to kernelci.org and I don't see any issues that >> > could be caused by them. >> > >> > With this series I get the kernel to output to the panel in 0.5s, >> > instead of 2.8s. >> >> I think we're pretty close other than some minor comments. I would like >> to see ack's from Greg and some reviewed-bys from others. The subsystem >> changes are minor and there has been plenty of chance to comment, so I >> don't think acks from all subsystems are needed. >> >> Your branch is based on -next. Is there any dependence on something in >> -next? I want to get this into -next soon, but need a branch not based >> on -next. Please send me a pull request with the collected acks and >> minor comments I have addressed. > > Let me review this on Monday and I'll let you know... Hi Greg, hope you don't mind that I ping you regarding this, just in case it fell through some crack. Regards, Tomeu > thanks, > > greg k-h > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- 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
