linux-kernel - Re: [PATCH 1/2] soundwire: intel_auxdevice: enable pm

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Message-ID: <20230804094441.GR103419@ediswmail.ad.cirrus.com>
Date:   Fri, 4 Aug 2023 09:44:41 +0000
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     Bard Liao <yung-chuan.liao@...ux.intel.com>
CC:     <alsa-devel@...a-project.org>, <vkoul@...nel.org>,
        <vinod.koul@...aro.org>, <linux-kernel@...r.kernel.org>,
        <pierre-louis.bossart@...ux.intel.com>, <bard.liao@...el.com>
Subject: Re: [PATCH 1/2] soundwire: intel_auxdevice: enable pm_runtime
 earlier on startup

On Thu, Aug 03, 2023 at 02:52:19PM +0800, Bard Liao wrote:
> From: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> 
> As soon as the bus starts, physical peripheral devices may report as
> ATTACHED and set their status with pm_runtime_set_active() in their
> update_status()/io_init().
> 
> This is problematic with the existing code, since the parent
> pm_runtime status is changed to "active" after starting the bus. This
> creates a time window where the pm_runtime framework can report an
> issue, e.g.
> 
> "rt711 sdw:0:025d:0711:00: runtime PM trying to activate child device
> sdw:0:025d:0711:00 but parent (sdw-master-0) is not active"
> 
> This patch enables runtime_pm earlier to make sure the auxiliary
> device is pm_runtime active after powering-up, but before starting the
> bus.
> 
> This problem was exposed by recent changes in the timing of the bus
> reset, but was present in this driver since we introduced pm_runtime
> support.
> 
> Closes: https://github.com/thesofproject/linux/issues/4328
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> Reviewed-by: Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>
> Reviewed-by: Rander Wang <rander.wang@...el.com>
> Signed-off-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
> ---

Doesn't seem to cause any problems on my SoundWire devices, so
very loosely:

Tested-by: Charles Keepax <ckeepax@...nsource.cirrus.com>

Thanks,
Charles