Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.36 as permitted sender) client-ip=23.128.96.36;
Date:   Fri, 13 Oct 2023 13:25:03 +0200
From:   Andreas Kemnade <andreas@kemnade.info>
To:     =?UTF-8?B?UMOpdGVy?= Ujfalusi <peter.ujfalusi@gmail.com>
Cc:     Tony Lindgren <tony@atomide.com>, bcousson@baylibre.com,
        robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        conor+dt@kernel.org, lgirdwood@gmail.com, broonie@kernel.org,
        perex@perex.cz, tiwai@suse.com, jarkko.nikula@bitmer.com,
        dmitry.torokhov@gmail.com, linux-omap@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        alsa-devel@alsa-project.org
Subject: Re: [PATCH 1/3] ASoC: ti: omap-mcbsp: Ignore errors for getting
 fck_src
Message-ID: <20231013132503.25d63933@aktux>
In-Reply-To: <db511d14-f2fe-4b4e-bd13-223e7a33f933@gmail.com>
References: <20230705190324.355282-1-andreas@kemnade.info>
        <20230705190324.355282-2-andreas@kemnade.info>
        <7d58d52d-2087-45af-b29e-2515b63ead13@gmail.com>
        <20230920063353.GQ5285@atomide.com>
        <dac768d2-2c66-4d6b-b3d3-d1ef69103c76@gmail.com>
        <20230921121626.GT5285@atomide.com>
        <20231006102348.GK34982@atomide.com>
        <20231006213003.0fbac87a@aktux>
        <20231007062518.GM34982@atomide.com>
        <20231007091156.588d7ba1@aktux>
        <db511d14-f2fe-4b4e-bd13-223e7a33f933@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8BIT
Precedence: bulk

On Thu, 12 Oct 2023 17:41:34 +0300
Péter Ujfalusi <peter.ujfalusi@gmail.com> wrote:

> On 07/10/2023 10:11, Andreas Kemnade wrote:
> >> OK good to hear it works, I'll send out fixes for omap4 and 5, seems
> >> the runtime PM warning is something different.
> >>  
> >>> omap-mcbsp 40124000.mcbsp: Runtime PM usage count underflow!
> >>> # cat /sys/bus/platform/devices/40124000.mcbsp/power/runtime_status 
> >>> active
> >>>
> >>> even with no sound.    
> >>  
> > Well, it is a regression caused by your fix. Without it (and not reverting
> > the already applied ignore patch), runtime is properly suspended. Don't know
> > why yet.  
> 
> I guess it is because of the pm_runtime_put_sync() in the
> omap2_mcbsp_set_clks_src() around the fclk re-parenting.
> That is a bit dubious thing for sure. We need to disable the device to
> be able to re-parent the fclk but if we disable the device it is going
> to be powered down, right? I think we have appropriate context handling,
> so it might work, but it is certainly not a rock solid code... If you
> have a stream running already, you don't really want to kill the McBSP.
> 
Ok, so if the device is powered of at omap2_mcbsp_set_clks_src() 
we get the usage count underflow, and the counter is incremented
immediately again in the runtime put function. So things get out of balance...
I'll check Tony's fix here.

> The problem is that this mux is outside of the McBSP IP, so we need a
> system level (iow, clk API) way to change it runtime.
> 
> What is the machine driver where this happens? If you set the sysclk in
> hw_params of the machine driver, it will be OK, but if you do that in
> probe time then it is likely going to fail as you experienced
> 
As you see in the other patches of this series,
it is a simple-audio-card with a tlv320aic3x codec
in combination with the mcbsp.

Regards,
Andreas