Re: [PATCH 2/2] soc: imx: gpcv2: prepare bus clocks early

From: Luca Ceresoli <luca.ceresoli@bootlin.com>
To: Lucas Stach <l.stach@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>, Marek Vasut <marex@denx.de>,
	patchwork-lst@pengutronix.de,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/2] soc: imx: gpcv2: prepare bus clocks early
Date: Mon, 5 Jun 2023 10:06:39 +0200	[thread overview]
Message-ID: <20230605100639.54d77ac5@booty> (raw)
In-Reply-To: <20230602185417.4098937-2-l.stach@pengutronix.de>

Hi Lucas,

On Fri,  2 Jun 2023 20:54:17 +0200
Lucas Stach <l.stach@pengutronix.de> wrote:

> Prepare the bus clocks during PGC domain driver probe. This avoids a
> potential deadlock when there a clock providers inside the domain,
> as this might end up trying to take the CCF prepare_lock from two
> different contexts, when runtime PM is trying to resume the PGC domain
> for the clock provider. By keeping the bus clocks prepared as long as
> there is a PGC domain driver attached, we don't need to take the
> prepare_lock in the domain power up/down paths.
> 
> We don't want to do this for regular reset clocks, as this might lead
> to some PLLs being kept prepared that could otherwise be shut down.
> For the bus clocks this isn't a concern, as all the bus clocks are
> derived from always-on system PLLs.
> 
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

...

> @@ -1343,10 +1355,19 @@ static int imx_pgc_domain_probe(struct platform_device *pdev)
>  		regmap_update_bits(domain->regmap, domain->regs->map,
>  				   domain->bits.map, domain->bits.map);
>  
> +	if (domain->bus_clocks) {
> +		ret = clk_bulk_prepare(domain->num_clks, domain->clks);
> +		if (ret) {
> +			dev_err(domain->dev,
> +				"Failed to prepare domain's clocks\n");
> +			goto out_domain_unmap;
> +		}
> +	}
> +
>  	ret = pm_genpd_init(&domain->genpd, NULL, true);
>  	if (ret) {
>  		dev_err(domain->dev, "Failed to init power domain\n");
> -		goto out_domain_unmap;
> +		goto out_disable_clocks;
>  	}
>  
>  	if (IS_ENABLED(CONFIG_LOCKDEP) &&
> @@ -1364,6 +1385,9 @@ static int imx_pgc_domain_probe(struct platform_device *pdev)
>  
>  out_genpd_remove:
>  	pm_genpd_remove(&domain->genpd);
> +out_disable_clocks:
> +	if (domain->bus_clocks)
> +		clk_bulk_unprepare(domain->num_clks, domain->clks);

Shouldn't the label be "out_unprepare_clocks"?

Luca

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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