linux-kernel - Re: [RFC PATCH 1/3] soc/tegra: pmc: Initialise power partitions early

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Message-ID: <20160630101732.GG1776@ulmo.ba.sec>
Date:	Thu, 30 Jun 2016 12:17:32 +0200
From:	Thierry Reding <thierry.reding@...il.com>
To:	Jon Hunter <jonathanh@...dia.com>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	Alexandre Courbot <gnurou@...il.com>,
	linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 1/3] soc/tegra: pmc: Initialise power partitions early

On Tue, Jun 28, 2016 at 12:20:42PM +0100, Jon Hunter wrote:
> If CONFIG_PM_GENERIC_DOMAINS is not enabled, then power partitions
> associated with a device will not be enabled automatically by the PM
> core when the device is in use. To avoid situations where a device in
> a power partition is to be used but the partition is not enabled,
> initialise the power partitions for Tegra early in the boot process and
> if CONFIG_PM_GENERIC_DOMAINS is not enabled, then power on all
> partitions defined in the device-tree blob.
> 
> Note that if CONFIG_PM_GENERIC_DOMAINS is not enabled, after the
> partitions are turned on, the clocks and resets used as part of the
> sequence for turning on the partition are released again as they are no
> longer needed by the PMC driver. Another benefit of this is that this
> avoids any issues of sharing resets between the PMC driver and other
> device drivers that may wish to independently control a particular
> reset.
> 
> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
> ---
>  drivers/soc/tegra/pmc.c | 33 ++++++++++++++++++++++-----------
>  1 file changed, 22 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
> index 1f702538f8ec..64678ff2173e 100644
> --- a/drivers/soc/tegra/pmc.c
> +++ b/drivers/soc/tegra/pmc.c
> @@ -788,7 +788,7 @@ error:
>  static void tegra_powergate_add(struct tegra_pmc *pmc, struct device_node *np)
>  {
>  	struct tegra_powergate *pg;
> -	bool off;
> +	bool off, err = true;
>  	int id;
>  
>  	pg = kzalloc(sizeof(*pg), GFP_KERNEL);
> @@ -819,6 +819,9 @@ static void tegra_powergate_add(struct tegra_pmc *pmc, struct device_node *np)
>  	if (tegra_powergate_of_get_resets(pg, np, off))
>  		goto remove_clks;
>  
> +	if (!IS_ENABLED(CONFIG_PM_GENERIC_DOMAINS))
> +		goto power_on_cleanup;
> +
>  	pm_genpd_init(&pg->genpd, NULL, off);
>  
>  	if (of_genpd_add_provider_simple(np, &pg->genpd))
> @@ -828,6 +831,11 @@ static void tegra_powergate_add(struct tegra_pmc *pmc, struct device_node *np)
>  
>  	return;
>  
> +power_on_cleanup:
> +	if (off)
> +		WARN_ON(tegra_powergate_power_up(pg, true));
> +	err = false;
> +
>  remove_resets:
>  	while (pg->num_resets--)
>  		reset_control_put(pg->resets[pg->num_resets]);
> @@ -845,14 +853,23 @@ free_mem:
>  	kfree(pg);
>  
>  error:
> -	dev_err(pmc->dev, "failed to create power domain for %s\n", np->name);
> +	if (err)
> +		dev_err(pmc->dev, "failed to configure partition %s\n",
> +			np->name);

This is beginning to look very spaghetti-like. Do we really need the
error message here? Could we instead add more explicit error messages
before the gotos above?

Thierry

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