From: Wolfram Sang <wsa@the-dreams.de>
To: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: linux-i2c@vger.kernel.org, Keijo Vaara <ferdasyn@rocketmail.com>,
linux-input@vger.kernel.org, Bjorn Helgaas <helgaas@kernel.org>,
"Rafael J . Wysocki" <rafael@kernel.org>,
stable@vger.kernel.org
Subject: Re: [PATCH] i2c: Prevent runtime suspend of adapter when Host Notify is required
Date: Thu, 2 May 2019 18:43:46 +0200 [thread overview]
Message-ID: <20190502164346.GE11535@kunai> (raw)
In-Reply-To: <20190430142322.15013-1-jarkko.nikula@linux.intel.com>
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On Tue, Apr 30, 2019 at 05:23:22PM +0300, Jarkko Nikula wrote:
> Multiple users have reported their Synaptics touchpad has stopped
> working between v4.20.1 and v4.20.2 when using SMBus interface.
>
> The culprit for this appeared to be commit c5eb1190074c ("PCI / PM: Allow
> runtime PM without callback functions") that fixed the runtime PM for
> i2c-i801 SMBus adapter. Those Synaptics touchpad are using i2c-i801
> for SMBus communication and testing showed they are able to get back
> working by preventing the runtime suspend of adapter.
>
> Normally when i2c-i801 SMBus adapter transmits with the client it resumes
> before operation and autosuspends after.
>
> However, if client requires SMBus Host Notify protocol, what those
> Synaptics touchpads do, then the host adapter must not go to runtime
> suspend since then it cannot process incoming SMBus Host Notify commands
> the client may send.
>
> Fix this by keeping I2C/SMBus adapter active in case client requires
> Host Notify.
>
> Reported-by: Keijo Vaara <ferdasyn@rocketmail.com>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=203297
> Fixes: c5eb1190074c ("PCI / PM: Allow runtime PM without callback functions")
> Cc: stable@vger.kernel.org # v4.20+
> Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Applied to for-current-fixed, thanks!
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prev parent reply other threads:[~2019-05-02 16:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-30 14:23 [PATCH] i2c: Prevent runtime suspend of adapter when Host Notify is required Jarkko Nikula
2019-04-30 15:42 ` Rafael J. Wysocki
2019-05-02 8:07 ` Keijo Vaara
2019-05-02 16:43 ` Wolfram Sang [this message]
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