linux-kernel - Re: [PATCH 4/4] ARM: multi_v7_defconfig: Switch AXP20x driver from module to built-in

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Date:   Tue, 6 Jun 2017 12:45:17 -0700
From:   Kevin Hilman <khilman@...libre.com>
To:     Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:     Rask Ingemann Lambertsen <rask@...melder.dk>,
        Chen-Yu Tsai <wens@...e.org>,
        Russell King <linux@...linux.org.uk>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] ARM: multi_v7_defconfig: Switch AXP20x driver from
 module to built-in

On Mon, May 22, 2017 at 12:44 AM, Maxime Ripard
<maxime.ripard@...e-electrons.com> wrote:
> Hi Kevin,
>
> On Thu, May 18, 2017 at 11:59:50AM -0700, Kevin Hilman wrote:
>> On Fri, Mar 17, 2017 at 10:39 AM, Kevin Hilman <khilman@...libre.com> wrote:
>> > On Fri, Feb 10, 2017 at 12:42 AM, Maxime Ripard
>> > <maxime.ripard@...e-electrons.com> wrote:
>> >> On Wed, Feb 08, 2017 at 11:09:31PM +0100, Rask Ingemann Lambertsen wrote:
>> >>> The AXP20X regulator support is currently built as a module, which means
>> >>> it's not available until the root fs has been mounted, but the boot loader
>> >>> might not have enabled the required regulators, so build their drivers
>> >>> into the kernel.
>> >>>
>> >>> Signed-off-by: Rask Ingemann Lambertsen <rask@...melder.dk>
>> >>
>> >> Queued for 4.12.
>> >
>> > Hello, kernelci.org is reporting boot failures on sun5i-r8-chip in
>> > linux-next[1]  for a few days and with a variety of defconfigs. I
>> > bisected it[2] down to this patch.
>> >
>> > I verified that reverting this patch on top of next-20170310 makes my
>> > chip board boot again.
>>
>> FYI... this board is still broken in linux-next (and now in mainline),
>> and reverting $SUBJECT patch still makes it work.
>>
>> Is nobody else using mainline on this board?
>
> I thought about that during the weekend, and it might just be a
> symptom.
>
> The CHIP has brown out issues, especially when you enable the WiFi
> chip, which should happen around the time of the failure when the PMIC
> regulator support is compiled as a module.
>
> We mitigate that in upstream's U-Boot by enabling the two regulators
> for the WiFi chip in U-boot, which levels a bit the current over the
> boot.
>
> You have a few ways to prevent that from happening. Having a better
> power supply / cable will help, I'm not sure how reasonable that is.
>
> Another thing that can work is, if your USB plugs can take it, to
> increase the overcurrent trigger in the PMIC, ideally in U-Boot.
>
> The last, and probably cleaner one, would be to just power it through
> the 5v input on its header, and not the USB. There's not current
> limitation there, so it shouldn't cause any problems anymore.

I'm now powering the board via the header (5V to the CHG-IN pin) and
it doesn't change anything.  Still fails in the same way, and
reverting $SUBJECT defconfig patch makes it work again.

Kevin