From: Petr Vorel <petr.vorel@gmail.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>,
MSM <linux-arm-msm@vger.kernel.org>,
Andy Gross <agross@kernel.org>, Rob Herring <robh+dt@kernel.org>,
Ricardo Ribalda <ribalda@kernel.org>,
Konrad Dybcio <konradybcio@gmail.com>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>
Subject: Re: [PATCH 1/1] arm64: dts: qcom: msm8994: Reserve gpio ranges
Date: Thu, 8 Apr 2021 21:02:48 +0200 [thread overview]
Message-ID: <YG9TWEJlpDmNeeit@pevik> (raw)
In-Reply-To: <CACRpkdZQ8qiqFPa0X8deVjZ7nLn_E6s8fmJdr5Ji8AuyJms1ug@mail.gmail.com>
> On Tue, Apr 6, 2021 at 12:52 AM Bjorn Andersson
> <bjorn.andersson@linaro.org> wrote:
> > On Mon 05 Apr 15:02 CDT 2021, Petr Vorel wrote:
> > > Simple testing with /sys/class/gpio/export showed that 85-88.
> > > 3 disables UART. I expect 0-2 are also reserved as on other msm8998.
> > Are you saying that once you export these gpios the uart stops working?
> That might be a Fixes: but certainly not a regression.
> Using GPIO sysfs access is dangerous and if someone enables it into
> their kernel (which requires setting CONFIG_EXPERT) they are
> certainly aware that they are taking a risk. (Same goes for using
> the character device from userspace.)
Not sure if we understand each other. You might think I export GPIO from
userspace on mainline kernel or use CONFIG_EXPERT. None of these is true.
The real problem is that mainline kernel compiled with defconfig resets really
early, thus v2 of this patch [2] is needed.
I just exported GPIO on *downstream* kernel to observe the behaviour.
It was just a simple way for me to find GPIOs which cause reset.
(having docs would be great)
And there is similar reset much later but still before reaching initramfs
in loop_init since a99163e9e708 (during loop_add() on lo->lo_number: 3). And
if I disable CONFIG_BLK_DEV_LOOP, it resets right after reaching initramfs.
I guess that's another problem with DT, but haven't got much further.
But that's a separate problem, gpio-reserved-ranges = <85 4> on tlmm [2]
is still some improvement.
Kind regards,
Petr
[2] https://lore.kernel.org/linux-arm-msm/20210406202936.22500-1-petr.vorel
> Yours,
> Linus Walleij
next prev parent reply other threads:[~2021-04-08 19:02 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-05 20:02 [PATCH 1/1] arm64: dts: qcom: msm8994: Reserve gpio ranges Petr Vorel
2021-04-05 20:09 ` Ricardo Ribalda Delgado
2021-04-05 20:15 ` Petr Vorel
2021-04-05 22:52 ` Bjorn Andersson
2021-04-06 4:38 ` Petr Vorel
2021-04-08 7:17 ` Linus Walleij
2021-04-08 19:02 ` Petr Vorel [this message]
2021-04-08 20:05 ` Konrad Dybcio
2021-04-08 21:40 ` Linus Walleij
2021-04-09 3:19 ` Petr Vorel
2021-04-09 3:37 ` Bjorn Andersson
2021-04-10 5:52 ` Petr Vorel
2021-04-10 9:16 ` Konrad Dybcio
2021-04-10 17:20 ` Petr Vorel
2021-04-12 17:48 ` Petr Vorel
2021-04-08 21:35 ` Linus Walleij
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