linux-kernel - Re: [PATCH] soundwire: master: use pm_runtime_set

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Message-ID: <20201202071942.GH8403@vkoul-mobl>
Date:   Wed, 2 Dec 2020 12:49:42 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Bard Liao <yung-chuan.liao@...ux.intel.com>
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, jank@...ence.com,
        srinivas.kandagatla@...aro.org, rander.wang@...ux.intel.com,
        ranjani.sridharan@...ux.intel.com, hui.wang@...onical.com,
        pierre-louis.bossart@...ux.intel.com, sanyog.r.kale@...el.com,
        mengdong.lin@...el.com, bard.liao@...el.com
Subject: Re: [PATCH] soundwire: master: use pm_runtime_set_active() on add

On 24-11-20, 21:07, Bard Liao wrote:
> From: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> 
> The 'master' device acts as a glue layer used during bus
> initialization only, and it needs to be 'transparent' for pm_runtime
> management. Its behavior should be that it becomes active when one of
> its children becomes active, and suspends when all of its children are
> suspended.
> 
> In our tests on Intel platforms, we routinely see these sort of
> warnings on the initial boot:
> 
> [ 21.447345] rt715 sdw:3:25d:715:0: runtime PM trying to activate
> child device sdw:3:25d:715:0 but parent (sdw-master-3) is not active
> 
> This is root-caused to a missing setup to make the device 'active' on
> probe. Since we don't want the device to remain active forever after
> the probe, the autosuspend configuration is also enabled at the end of
> the probe - the device will actually autosuspend only in the case
> where there are no devices physically attached. In practice, the
> master device will suspend when all its children are no longer active.

Applied, thanks

-- 
~Vinod