linux-kernel - Re: [PATCH 1/1] thermal/drivers/imx_sc_thermal: return -EAGAIN when SCFW turn off resource

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Message-ID: <ZNz5Drb+EVLjWxRV@lizhi-Precision-Tower-5810>
Date:   Wed, 16 Aug 2023 12:28:44 -0400
From:   Frank Li <Frank.li@....com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>, imx@...ts.linux.dev,
        Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH 1/1] thermal/drivers/imx_sc_thermal: return -EAGAIN when
 SCFW turn off resource

On Wed, Aug 16, 2023 at 10:44:32AM +0200, Daniel Lezcano wrote:
> 
> Hi Frank,
> 
> sorry for the delay
> 
> On 14/07/2023 19:19, Frank Li wrote:
> > On Thu, Jul 13, 2023 at 02:49:54PM +0200, Daniel Lezcano wrote:
> > > On 12/07/2023 23:05, Frank Li wrote:
> > > > Avoid endless print following message when SCFW turns off resource.
> > > >    [ 1818.342337] thermal thermal_zone0: failed to read out thermal zone (-1)
> > > > 
> > > > Signed-off-by: Frank Li <Frank.Li@....com>
> > > > ---
> > > >    drivers/thermal/imx_sc_thermal.c | 4 +++-
> > > >    1 file changed, 3 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/thermal/imx_sc_thermal.c b/drivers/thermal/imx_sc_thermal.c
> > > > index 8d6b4ef23746..0533d58f199f 100644
> > > > --- a/drivers/thermal/imx_sc_thermal.c
> > > > +++ b/drivers/thermal/imx_sc_thermal.c
> > > > @@ -58,7 +58,9 @@ static int imx_sc_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
> > > >    	hdr->size = 2;
> > > >    	ret = imx_scu_call_rpc(thermal_ipc_handle, &msg, true);
> > > > -	if (ret)
> > > > +	if (ret == -EPERM) /* NO POWER */
> > > > +		return -EAGAIN;
> > > 
> > > Isn't there a chain call somewhere when the resource is turned off, so the
> > > thermal zone can be disabled?
> > 
> > A possible place in drivers/firmware/imx/scu-pd.c. but I am not sure how to
> > get thermal devices. I just found a API thermal_zone_get_zone_by_name(). I
> > am not sure if it is good to depend on "name", which add coupling between
> > two drivers and if there are external thermal devices(such as) has the
> > same name, it will wrong turn off.
> 
> Correct
> 
> > If add power domain notification in thermal driver, I am not how to get
> > other devices's pd in thermal driver.
> > 
> > Any example I can refer?
> > 
> > Or this is simple enough solution.
> 
> The solution works for removing the error message but it does not solve the
> root cause of the issue. The thermal zone keeps monitoring while the sensor
> is down.
> 
> So the question is why the sensor is shut down if it is in use?

Do you know if there are any code I reference? I supposed it is quite common.

Frank

> 
> 
> 
> > > 
> > > > +	else if (ret)
> > > >    		return ret;
> > > >    	*temp = msg.data.resp.celsius * 1000 + msg.data.resp.tenths * 100;
> > > 
> > > -- 
> > > <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
> > > 
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> > > 
> 
> -- 
> <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs
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