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From: Dmitry Osipenko <digetx@gmail.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Laxman Dewangan <ldewangan@nvidia.com>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Peter Geis <pgwipeout@gmail.com>,
	linux-tegra@vger.kernel.org,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 2/2] gpio: tegra: Use raw_spinlock
Date: Wed, 4 Nov 2020 18:03:07 +0300	[thread overview]
Message-ID: <274bca60-6a8f-773b-aff1-2a897376a6b1@gmail.com> (raw)
In-Reply-To: <CAHp75VeJrQCxaCR+6u79=k=EP7y=LpEsytp6MWQ+UGz+oFXP6A@mail.gmail.com>

04.11.2020 17:47, Andy Shevchenko пишет:
> On Wed, Nov 4, 2020 at 3:27 PM Dmitry Osipenko <digetx@gmail.com> wrote:
>>
>> Use raw_spinlock in order to fix spurious messages about invalid context
>> when spinlock debugging is enabled. This happens because there is a legit
>> nested raw_spinlock->spinlock locking which debug code can't recognize and
>> handle.
> 
> This sounds like papering over a problem that exists somewhere else.
> 
> What I would rather make as a selling point is that raw spin locks are
> necessary to be in the RT kernel for IRQ chips.

This should be a well-known problem because other GPIO drivers also have
it.

For example this one:

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20201104&id=023892ec80f0efcffe22045e92bb89f3f1480f2d

Although, looking at it again, I think there is no real need to change
the dbc_lock since it doesn't relate to the IRQ. Perhaps this could be
improved in a v2.

  reply	other threads:[~2020-11-04 15:03 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-04 13:26 [PATCH v1 1/2] gpio: tegra: Add lockdep class Dmitry Osipenko
2020-11-04 13:26 ` [PATCH v1 2/2] gpio: tegra: Use raw_spinlock Dmitry Osipenko
2020-11-04 14:47   ` Andy Shevchenko
2020-11-04 15:03     ` Dmitry Osipenko [this message]
2020-11-06 14:31 ` [PATCH v1 1/2] gpio: tegra: Add lockdep class Bartosz Golaszewski

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