linux-kernel - Re: [PATCH v2 28/48] soc/tegra: Introduce core power domain driver

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Message-ID: <20201222064029.duuzcsj53rt7xzvt@vireshk-i7>
Date:   Tue, 22 Dec 2020 12:10:29 +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>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-media@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 28/48] soc/tegra: Introduce core power domain driver

On 17-12-20, 21:06, Dmitry Osipenko wrote:
> +++ b/drivers/soc/tegra/core-power-domain.c
> @@ -0,0 +1,125 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * NVIDIA Tegra SoC Core Power Domain Driver
> + */
> +
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_domain.h>
> +#include <linux/pm_opp.h>
> +#include <linux/slab.h>
> +
> +#include <soc/tegra/common.h>
> +
> +static struct lock_class_key tegra_core_domain_lock_class;
> +static bool tegra_core_domain_state_synced;
> +
> +static int tegra_genpd_set_performance_state(struct generic_pm_domain *genpd,
> +					     unsigned int level)
> +{
> +	struct dev_pm_opp *opp;
> +	int err;
> +
> +	opp = dev_pm_opp_find_level_ceil(&genpd->dev, &level);

We don't need ceil or floor versions for level, but rather _exact() version. Or
maybe just call it dev_pm_opp_find_level().

> +	if (IS_ERR(opp)) {
> +		dev_err(&genpd->dev, "failed to find OPP for level %u: %pe\n",
> +			level, opp);
> +		return PTR_ERR(opp);
> +	}
> +
> +	err = dev_pm_opp_set_voltage(&genpd->dev, opp);

IIUC, you implemented this callback because you want to use the voltage triplet
present in the OPP table ?

And so you are setting the regulator ("power") later in this patch ?

I am not in favor of implementing this routine, as it just adds a wrapper above
the regulator API. What you should be doing rather is get the regulator by
yourself here (instead of depending on the OPP core). And then you can do
dev_pm_opp_get_voltage() here and set the voltage yourself. You may want to
implement a version supporting triplet here though for the same.

And you won't require the sync version of the API as well then.

-- 
viresh