On Wed, Sep 30, 2015 at 12:09:27PM +0200, Tomeu Vizoso wrote: > 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. It's on my todo list, sorry, am at a conference for the next few days, didn't get to it on Monday, hopefully soon... greg "my todo list is too long" k-h -- 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
