linux-kernel - Re: [PATCH v8 01/34] opp: Add dev_pm_opp

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Message-ID: <20210817075515.vyyv7z37e6jcrhsl@vireshk-i7>
Date:   Tue, 17 Aug 2021 13:25:15 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Mikko Perttunen <mperttunen@...dia.com>,
        Peter Chen <peter.chen@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Lucas Stach <dev@...xeye.de>, Stefan Agner <stefan@...er.ch>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-staging@...ts.linux.dev, linux-spi@...r.kernel.org,
        linux-pwm@...r.kernel.org, linux-mtd@...ts.infradead.org,
        linux-mmc@...r.kernel.org, linux-media@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v8 01/34] opp: Add dev_pm_opp_sync() helper

On 17-08-21, 04:27, Dmitry Osipenko wrote:
> Add dev_pm_opp_sync() helper which syncs OPP table with hardware state
> and vice versa.
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/opp/core.c     | 42 +++++++++++++++++++++++++++++++++++++++---
>  include/linux/pm_opp.h |  6 ++++++
>  2 files changed, 45 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 5543c54dacc5..18016e49605f 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -939,7 +939,8 @@ static int _set_required_opps(struct device *dev,
>  	return ret;
>  }
>  
> -static void _find_current_opp(struct device *dev, struct opp_table *opp_table)
> +static struct dev_pm_opp *
> +_find_current_opp(struct device *dev, struct opp_table *opp_table)
>  {
>  	struct dev_pm_opp *opp = ERR_PTR(-ENODEV);
>  	unsigned long freq;
> @@ -961,7 +962,7 @@ static void _find_current_opp(struct device *dev, struct opp_table *opp_table)
>  		mutex_unlock(&opp_table->lock);
>  	}
>  
> -	opp_table->current_opp = opp;
> +	return opp;
>  }
>  
>  static int _disable_opp_table(struct device *dev, struct opp_table *opp_table)
> @@ -1003,7 +1004,7 @@ static int _set_opp(struct device *dev, struct opp_table *opp_table,
>  
>  	/* Find the currently set OPP if we don't know already */
>  	if (unlikely(!opp_table->current_opp))
> -		_find_current_opp(dev, opp_table);
> +		opp_table->current_opp = _find_current_opp(dev, opp_table);
>  
>  	old_opp = opp_table->current_opp;
>  
> @@ -2931,3 +2932,38 @@ int dev_pm_opp_sync_regulators(struct device *dev)
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_opp_sync_regulators);
> +
> +/**
> + * dev_pm_opp_sync() - Sync OPP state
> + * @dev:	device for which we do this operation
> + *
> + * Initialize OPP table accordingly to current clock rate or
> + * first available OPP if clock not available for this device.
> + *
> + * Return: 0 on success or a negative error value.
> + */
> +int dev_pm_opp_sync(struct device *dev)
> +{
> +	struct opp_table *opp_table;
> +	struct dev_pm_opp *opp;
> +	int ret = 0;
> +
> +	/* Device may not have OPP table */
> +	opp_table = _find_opp_table(dev);
> +	if (IS_ERR(opp_table))
> +		return 0;
> +
> +	if (!_get_opp_count(opp_table))
> +		goto put_table;
> +
> +	opp = _find_current_opp(dev, opp_table);
> +	ret = _set_opp(dev, opp_table, opp, opp->rate);

And I am not sure how this will end up working, since new OPP will be
equal to old one. Since I see you call this from resume() at many
places.

what exactly are you trying to do here ? Those details would be good
to have in commit log as well, I haven't really followed V7 of your
series.

-- 
viresh