From: Thierry Reding <thierry.reding@gmail.com>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: Wolfram Sang <wsa@the-dreams.de>,
Jon Hunter <jonathanh@nvidia.com>,
linux-i2c@vger.kernel.org, linux-tegra@vger.kernel.org
Subject: Re: [PATCH 2/5] i2c: tegra: Restore pinmux on system resume
Date: Tue, 19 May 2020 18:07:35 +0200 [thread overview]
Message-ID: <20200519160735.GB2113674@ulmo> (raw)
In-Reply-To: <86fee5a3-fe2f-05ab-bc05-1c441d2845e9@gmail.com>
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On Sat, May 09, 2020 at 06:35:41PM +0300, Dmitry Osipenko wrote:
> > 2. Could you please explain why I2C driver has to care about restoring
> > the pinmux state? Why pinctrl driver isn't doing that for I2C and
> > everything else?
>
> Although, now I see what you meant in the commit's message.
>
> Perhaps the "their I2C controllers may have lost the pinmux state in
> hardware" paragraph should be removed from the commit's message because
> it's irrelevant to this patch. The pinctrl state is changed once
> tegra_i2c_runtime_resume() is invoked and it is not about the change
> made by this patch.
The pinctrl state is changed in tegra_i2c_runtime_resume() *only if*
tegra_i2c_runtime_resume() has previously been called. So this patch
does indeed cause the pinmux to be restored, even though it does so
indirectly.
I think that paragraph is necessary to explain that. It's the pinctrl
that doesn't "notice" that the actual pinctrl state has changed from
"I2C" to "idle", so on resume it still thinks we're at "I2C" and won't
try to reapply the same state. Calling tegra_i2c_runtime_suspend() is
making sure that pinctrl explicitly switches to "idle", so that during
resume it will apply the "I2C" state since it is different from "idle".
Thierry
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next prev parent reply other threads:[~2020-05-19 16:07 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-06 19:33 [PATCH 0/5] i2c: tegra: Various fixes and improvements Thierry Reding
2020-05-06 19:33 ` [PATCH 1/5] Revert "i2c: tegra: Fix suspending in active runtime PM state" Thierry Reding
2020-05-06 19:33 ` [PATCH 2/5] i2c: tegra: Restore pinmux on system resume Thierry Reding
2020-05-06 22:43 ` mirq-test
2020-05-07 10:03 ` Thierry Reding
2020-05-07 12:20 ` Michał Mirosław
2020-05-07 21:50 ` Dmitry Osipenko
2020-05-08 10:31 ` Thierry Reding
2020-05-08 15:00 ` Dmitry Osipenko
2020-05-09 15:35 ` Dmitry Osipenko
2020-05-19 16:07 ` Thierry Reding [this message]
2020-05-19 15:57 ` Thierry Reding
2020-05-08 15:05 ` Dmitry Osipenko
2020-05-06 19:33 ` [PATCH 3/5] i2c: tegra: Keep IRQs enabled during suspend/resume Thierry Reding
2020-05-06 19:33 ` [PATCH 4/5] i2c: tegra: Better handle case where CPU0 is busy for a long time Thierry Reding
2020-05-06 19:33 ` [PATCH 5/5] i2c: tegra: Synchronize DMA before termination Thierry Reding
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