linux-kernel - Re: [PATCH v2] dma: qcom: bam_dma: Manage clocks when controlled

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Message-ID: <20210127013355.GF17701@dragon>
Date:   Wed, 27 Jan 2021 09:33:56 +0800
From:   Shawn Guo <shawn.guo@...aro.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     agross@...nel.org, bjorn.andersson@...aro.org,
        dan.j.williams@...el.com, vkoul@...nel.org,
        srinivas.kandagatla@...aro.org, linux-arm-msm@...r.kernel.org,
        dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] dma: qcom: bam_dma: Manage clocks when
 controlled_remotely is set

On Tue, Jan 26, 2021 at 04:18:59PM -0500, Thara Gopinath wrote:
> When bam dma is "controlled remotely", thus far clocks were not controlled
> from the Linux. In this scenario, Linux was disabling runtime pm in bam dma
> driver and not doing any clock management in suspend/resume hooks.
> 
> With introduction of crypto engine bam dma, the clock is a rpmh resource
> that can be controlled from both Linux and TZ/remote side.  Now bam dma
> clock is getting enabled during probe even though the bam dma can be
> "controlled remotely". But due to clocks not being handled properly,
> bam_suspend generates a unbalanced clk_unprepare warning during system
> suspend.
> 
> To fix the above issue and to enable proper clock-management, this patch
> enables runtim-pm and handles bam dma clocks in suspend/resume hooks if
> the clock node is present irrespective of controlled_remotely property.
> 
> Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>

Reviewed-by: Shawn Guo <shawn.guo@...aro.org>