Re: FAILED: patch "[PATCH] pinctrl: baytrail: Really serialize all register accesses" failed to apply to 4.19-stable tree

[Sasha Levin <sashal@kernel.org>]

On Sun, Dec 29, 2019 at 04:46:52PM +0100, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 4.19-stable tree.
>If someone wants it applied there, or to any other stable or longterm
>tree, then please email the backport, including the original git commit
>id to <stable@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From 40ecab551232972a39cdd8b6f17ede54a3fdb296 Mon Sep 17 00:00:00 2001
>From: Hans de Goede <hdegoede@redhat.com>
>Date: Tue, 19 Nov 2019 16:46:41 +0100
>Subject: [PATCH] pinctrl: baytrail: Really serialize all register accesses
>
>Commit 39ce8150a079 ("pinctrl: baytrail: Serialize all register access")
>added a spinlock around all register accesses because:
>
>"There is a hardware issue in Intel Baytrail where concurrent GPIO register
> access might result reads of 0xffffffff and writes might get dropped
> completely."
>
>Testing has shown that this does not catch all cases, there are still
>2 problems remaining
>
>1) The original fix uses a spinlock per byt_gpio device / struct,
>additional testing has shown that this is not sufficient concurent
>accesses to 2 different GPIO banks also suffer from the same problem.
>
>This commit fixes this by moving to a single global lock.
>
>2) The original fix did not add a lock around the register accesses in
>the suspend/resume handling.
>
>Since pinctrl-baytrail.c is using normal suspend/resume handlers,
>interrupts are still enabled during suspend/resume handling. Nothing
>should be using the GPIOs when they are being taken down, _but_ the
>GPIOs themselves may still cause interrupts, which are likely to
>use (read) the triggering GPIO. So we need to protect against
>concurrent GPIO register accesses in the suspend/resume handlers too.
>
>This commit fixes this by adding the missing spin_lock / unlock calls.
>
>The 2 fixes together fix the Acer Switch 10 SW5-012 getting completely
>confused after a suspend resume. The DSDT for this device has a bug
>in its _LID method which reprograms the home and power button trigger-
>flags requesting both high and low _level_ interrupts so the IRQs for
>these 2 GPIOs continuously fire. This combined with the saving of
>registers during suspend, triggers concurrent GPIO register accesses
>resulting in saving 0xffffffff as pconf0 value during suspend and then
>when restoring this on resume the pinmux settings get all messed up,
>resulting in various I2C busses being stuck, the wifi no longer working
>and often the tablet simply not coming out of suspend at all.
>
>Cc: stable@vger.kernel.org
>Fixes: 39ce8150a079 ("pinctrl: baytrail: Serialize all register access")
>Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
>Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

There were quite a few variable/struct renames in the file which
resulted in conflicts. I've fixed them up and queued for all branches.

-- 
Thanks,
Sasha