linux-kernel - Re: [PATCH v2 6/9] PM / Domains: Don't attach devices in genpd with multi PM domains

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Date:   Wed, 30 May 2018 17:06:11 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        <linux-pm@...r.kernel.org>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Todor Tomov <todor.tomov@...aro.org>,
        "Rajendra Nayak" <rnayak@...eaurora.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Kevin Hilman <khilman@...nel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-tegra@...r.kernel.org>, "Rob Herring" <robh+dt@...nel.org>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2 6/9] PM / Domains: Don't attach devices in genpd with
 multi PM domains


On 29/05/18 11:04, Ulf Hansson wrote:
> The power-domain DT property may now contain a list of PM domain
> specifiers, which represents that a device are partitioned across multiple
> PM domains. This leads to a new situation in genpd_dev_pm_attach(), as only
> one PM domain can be attached per device.
> 
> To remain things simple for the most common configuration, when a single PM
> domain is used, let's treat the multiple PM domain case as being specific.
> 
> In other words, let's change genpd_dev_pm_attach() to check for multiple PM
> domains and prevent it from attach any PM domain for this case. Instead,
> leave this to be managed separately, from following changes to genpd.
> 
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: devicetree@...r.kernel.org
> Suggested-by: Jon Hunter <jonathanh@...dia.com>
> Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> ---
> 
> Changes in v2:
> 	- Minor update to changelog to mention "PM domain specifiers" rather
> 	than a "list of phandles".
> 
> ---
>  drivers/base/power/domain.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 7ebf7993273a..12a20f21974d 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2229,10 +2229,10 @@ static void genpd_dev_pm_sync(struct device *dev)
>   * attaches the device to retrieved pm_domain ops.
>   *
>   * Returns 1 on successfully attached PM domain, 0 when the device don't need a
> - * PM domain or a negative error code in case of failures. Note that if a
> - * power-domain exists for the device, but it cannot be found or turned on,
> - * then return -EPROBE_DEFER to ensure that the device is not probed and to
> - * re-try again later.
> + * PM domain or when multiple power-domains exists for it, else a negative error
> + * code. Note that if a power-domain exists for the device, but it cannot be
> + * found or turned on, then return -EPROBE_DEFER to ensure that the device is
> + * not probed and to re-try again later.
>   */
>  int genpd_dev_pm_attach(struct device *dev)
>  {
> @@ -2243,10 +2243,18 @@ int genpd_dev_pm_attach(struct device *dev)
>  	if (!dev->of_node)
>  		return 0;
>  
> +	/*
> +	 * Devices with multiple PM domains must be attached separately, as we
> +	 * can only attach one PM domain per device.
> +	 */
> +	if (of_count_phandle_with_args(dev->of_node, "power-domains",
> +				       "#power-domain-cells") != 1)
> +		return 0;
> +
>  	ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
>  					"#power-domain-cells", 0, &pd_args);
>  	if (ret < 0)
> -		return 0;
> +		return ret;
>  
>  	mutex_lock(&gpd_list_lock);
>  	pd = genpd_get_from_provider(&pd_args);
> 

Acked-by: Jon Hunter <jonathanh@...dia.com>
Tested-by: Jon Hunter <jonathanh@...dia.com>

Cheers
Jon

-- 
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