linux-kernel - RE: [PATCH v4 2/3] clocksource: timer-cadence-ttc: Support TTC device configured as PWM

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Message-ID:
 <DS7PR12MB82495FE4A65F266D0857EB408F49A@DS7PR12MB8249.namprd12.prod.outlook.com>
Date: Wed, 9 Jul 2025 06:51:52 +0000
From: "Rao, Appana Durga Kedareswara" <appana.durga.kedareswara.rao@....com>
To: Uwe Kleine-König <ukleinek@...nel.org>
CC: "krzysztof.kozlowski+dt@...aro.org" <krzysztof.kozlowski+dt@...aro.org>,
	"daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>, "tglx@...utronix.de"
	<tglx@...utronix.de>, "Simek, Michal" <michal.simek@....com>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-pwm@...r.kernel.org"
	<linux-pwm@...r.kernel.org>, "git (AMD-Xilinx)" <git@....com>, "Vanukuri,
 Meher Thanmaiee" <MeherThanmaiee.Vanukuri@....com>
Subject: RE: [PATCH v4 2/3] clocksource: timer-cadence-ttc: Support TTC device
 configured as PWM

Ping!

<Snip>
> 
> Hi Uwe,
> 
> <Snip>
> > > +   /*
> > > +    * If pwm-cells property is present in TTC node,
> > > +    * it would be treated as PWM device.
> > > +    */
> > > +   if (of_property_read_bool(timer, "#pwm-cells")) {
> > > +           #if defined(CONFIG_PWM_CADENCE)
> > > +           ttc_config->is_pwm_mode = true;
> > > +                   return ttc_pwm_probe(pdev);
> >
> > strange indention. Maybe use
> >
> >       if (IS_REACHABLE(CONFIG_PWM_CADENCE))
> >
> > This is an unusal way to bind the PWM driver. I'd prefer creation of
> > separate device in the PWM case. I wonder if it can happen that
> > ttc_pwm_probe() is called during boot before pwm_init() completed. Or
> > use an auxbus device to distinguish between timer and pwm?
> >
> 
> Sorry for the delay in response the upstreaming of the TTC PWM driver was
> previously managed by Mubin. Since his departure from the organization, I
> will be taking over and continuing the upstreaming effort.
> 
> I have reviewed the v1 to v4 patch series along with all the associated
> feedback. In response to the concerns raised regarding the use of auxbus, I
> would like to propose an alternative solution: registering the PWM
> functionality as a separate platform driver using a distinct compatible string.
> This would allow the PWM driver to be probed only when the specific
> compatible string is present, while the timer driver would be used otherwise.
> 
> If this approach is agreeable, I will proceed with preparing the v5 patch
> accordingly(after fixing other review comments along with this change)
> otherwise will explore the auxbus device please let me know your thoughts.
> 
> Regards,
> Kedar.
> > > +           #else
> > > +                   return -ENODEV;
> > > +           #endif
> > > +   }
> > > +   dev_set_drvdata(&pdev->dev, ttc_config);
> > > +
> > >     if (initialized)
> > >             return 0;
> > >
> >
> > Best regards
> > Uwe