linux-kernel - Re: [PATCH 3/6] usb: cdns3-ti: add suspend/resume procedures for J7200

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Date:   Wed, 15 Nov 2023 13:37:51 +0200
From:   Roger Quadros <rogerq@...nel.org>
To:     Théo Lebrun <theo.lebrun@...tlin.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Peter Chen <peter.chen@...nel.org>,
        Pawel Laszczak <pawell@...ence.com>,
        Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Tero Kristo <kristo@...nel.org>
Cc:     linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 3/6] usb: cdns3-ti: add suspend/resume procedures for
 J7200



On 13/11/2023 16:26, Théo Lebrun wrote:
> Hardware initialisation is only done at probe. The J7200 USB controller
> is reset at resume because of power-domains toggling off & on. We
> therefore (1) toggle PM runtime at suspend/resume & (2) reconfigure the
> hardware at resume.

at probe we are doing a pm_runtime_get() and never doing a put thus
preventing any runtime PM.

> 
> Reuse the newly extracted cdns_ti_init_hw() function that contains the
> register write sequence.
> 
> We guard this behavior based on compatible to avoid modifying the
> current behavior on other platforms. If the controller does not reset
> we do not want to touch PM runtime & do not want to redo reg writes.
> 
> Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>
> ---
>  drivers/usb/cdns3/cdns3-ti.c | 48 +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 47 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/cdns3/cdns3-ti.c b/drivers/usb/cdns3/cdns3-ti.c
> index c331bcd2faeb..50b38c4b9c87 100644
> --- a/drivers/usb/cdns3/cdns3-ti.c
> +++ b/drivers/usb/cdns3/cdns3-ti.c
> @@ -197,6 +197,50 @@ static int cdns_ti_probe(struct platform_device *pdev)
>  	return error;
>  }
>  
> +#ifdef CONFIG_PM
> +
> +static int cdns_ti_suspend(struct device *dev)
> +{
> +	struct cdns_ti *data = dev_get_drvdata(dev);
> +
> +	if (!of_device_is_compatible(dev_of_node(dev), "ti,j7200-usb"))
> +		return 0;
> +
> +	pm_runtime_put_sync(data->dev);
> +
> +	return 0;

You might want to check suspend/resume ops in cdns3-plat and
do something similar here.

> +}
> +
> +static int cdns_ti_resume(struct device *dev)
> +{
> +	struct cdns_ti *data = dev_get_drvdata(dev);
> +	int ret;
> +
> +	if (!of_device_is_compatible(dev_of_node(dev), "ti,j7200-usb"))
> +		return 0;
> +
> +	ret = pm_runtime_get_sync(dev);
> +	if (ret < 0) {
> +		dev_err(dev, "pm_runtime_get_sync failed: %d\n", ret);
> +		goto err;
> +	}
> +
> +	cdns_ti_init_hw(data);
> +
> +	return 0;
> +
> +err:
> +	pm_runtime_put_sync(data->dev);
> +	pm_runtime_disable(data->dev);
> +	return ret;
> +}
> +
> +static const struct dev_pm_ops cdns_ti_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(cdns_ti_suspend, cdns_ti_resume)
> +};
> +
> +#endif /* CONFIG_PM */
> +
>  static int cdns_ti_remove_core(struct device *dev, void *c)
>  {
>  	struct platform_device *pdev = to_platform_device(dev);
> @@ -218,6 +262,7 @@ static void cdns_ti_remove(struct platform_device *pdev)
>  }
>  
>  static const struct of_device_id cdns_ti_of_match[] = {
> +	{ .compatible = "ti,j7200-usb", },
>  	{ .compatible = "ti,j721e-usb", },
>  	{ .compatible = "ti,am64-usb", },
>  	{},
> @@ -228,8 +273,9 @@ static struct platform_driver cdns_ti_driver = {
>  	.probe		= cdns_ti_probe,
>  	.remove_new	= cdns_ti_remove,
>  	.driver		= {
> -		.name	= "cdns3-ti",
> +		.name		= "cdns3-ti",
>  		.of_match_table	= cdns_ti_of_match,
> +		.pm		= pm_ptr(&cdns_ti_pm_ops),
>  	},
>  };
>  
> 

-- 
cheers,
-roger