Possible Regression due to c074fef5d36e ("of/platform: Defer probes of registered devices").

[Tomeu Vizoso]

On 26 October 2015 at 12:02, Geert Uytterhoeven <geert at linux-m68k.org> wrote:
> Hi Russell,
>
> On Mon, Oct 26, 2015 at 11:41 AM, Russell King - ARM Linux
> <linux at arm.linux.org.uk> wrote:
>> On Mon, Oct 26, 2015 at 10:56:03AM +0100, Geert Uytterhoeven wrote:
>>> On Mon, Oct 26, 2015 at 10:40 AM, Sylvain Rochet
>>> <sylvain.rochet at finsecur.com> wrote:
>>> > On Mon, Oct 26, 2015 at 12:20:39PM +0900, Simon Horman wrote:
>>> >> I have observed a possible regression in next-20151022
>>> >> due to c074fef5d36e ("of/platform: Defer probes of registered devices").
>>> >>
>>> >> The problem manifests on the r8a7791 based koelsch board.
>>> >> With the above patch present booting the board using the shmobile_defconfig
>>> >> results in no console output. While after reverting the above patch
>>> >> the boot proceeds all the way to user-space.
>>> >>
>>> >> With DEBUG_LL and EARLY_PRINTK enabled I was able to capture some console
>>> >> output. I have included both that boot log, and a log of boot all the way to
>>> >> userspace with the patch in question reverted.
>>> >>
>>> >> The problem does not seem to manifiest on other boards for other
>>> >> Renesas ARM  SoCs that I have access too. In particular the
>>> >> r8a7790 based lager board; the r8a7790 and r8a7791 are both members
>>> >> of the R-Car Gen2 family of SoCs.
>>> >
>>> > Atmel SoC hit this regresssion too, discussion about this issue is in
>>> > the following thread:
>>> >  https://lkml.org/lkml/2015/10/16/733
>>>
>>> More reading material in "[GIT PULL] On-demand device probing"
>>> (https://lkml.org/lkml/2015/10/14/126)
>>
>> It's quite obvious from the thread that the on-demand device probing is
>> *not* going to be merged for 4.4, and so it should not be in linux-next
>> at all.  Having it in linux-next, it's disrupting people's testing of
>> the 4.4 merge window material.
>>
>> Tomeu, please remove it so people can continue to test material
>> sheduled for the 4.4 merge window.  Thanks.
>
> Unfortunately we'll be stuck with next-20151022 for a while, due to KS...
>
> So you're only option is manually reverting
> commit 138d8b73e6a32aeacd3417106fbf740865da309e
> Merge: 0f1cba62520b6119 c074fef5d36e1c27
> Author: Rob Herring <robh at kernel.org>
> Date:   Thu Oct 15 08:26:41 2015 -0500
>
>     Merge branch 'on-demand-probes-for-next' of git://git.collabora.com/git/user
>
>     Pull on-demand probing series from Tomeu Vizoso.
>
> "git revert 138d8b73e6a32aeacd3417106fbf740865da309e -m 2" and fix
> the (many) conflicts :-(

It should be easier to just disable CONFIG_DELAY_DEVICE_PROBES. I sent
a patch that disables it by default here:

https://lkml.kernel.org/g/1445267602-12576-1-git-send-email-tomeu.vizoso@collabora.com

Regards,

Tomeu

> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
>
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