Re: [PATCH v4 3/9] usb: cdns3-ti: move reg writes from probe into ->runtime_resume()

[Roger Quadros <rogerq@kernel.org>]

Hi,

On 07/03/2024 11:55, Théo Lebrun wrote:
> The hardware initialisation register write sequence is only used at
> probe. Move it from being done at explicitely at probe to being done
> implicitely by pm_runtime_get_sync() that calls ->runtime_resume().

explicitly / implicitly

> 
> Keep devicetree parsing in probe and add a new field in the private
> struct to remember the USB2 refclk rate code computation result.
> 
> This opens the door to having the init sequence being executed later
> down the road, at system-wide resume for example. This is NOT currently
> happening because runtime PM is disabled at suspend without the
> refcount being affected.
> 
> Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
> ---
>  drivers/usb/cdns3/cdns3-ti.c | 90 +++++++++++++++++++++++++-------------------
>  1 file changed, 52 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/usb/cdns3/cdns3-ti.c b/drivers/usb/cdns3/cdns3-ti.c
> index 5945c4b1e11f..4c8a557e6a6f 100644
> --- a/drivers/usb/cdns3/cdns3-ti.c
> +++ b/drivers/usb/cdns3/cdns3-ti.c
> @@ -57,6 +57,7 @@ struct cdns_ti {
>  	unsigned vbus_divider:1;
>  	struct clk *usb2_refclk;
>  	struct clk *lpm_clk;
> +	int usb2_refclk_rate_code;
>  };
>  
>  static const int cdns_ti_rate_table[] = {	/* in KHZ */
> @@ -90,10 +91,8 @@ static int cdns_ti_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct device_node *node = pdev->dev.of_node;
>  	struct cdns_ti *data;
> -	int error;
> -	u32 reg;
> -	int rate_code, i;
>  	unsigned long rate;
> +	int error, i;
>  
>  	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>  	if (!data)
> @@ -133,7 +132,9 @@ static int cdns_ti_probe(struct platform_device *pdev)
>  		return -EINVAL;
>  	}
>  
> -	rate_code = i;
> +	data->usb2_refclk_rate_code = i;
> +	data->vbus_divider = device_property_read_bool(dev, "ti,vbus-divider");
> +	data->usb2_only = device_property_read_bool(dev, "ti,usb2-only");
>  
>  	pm_runtime_enable(dev);
>  	error = pm_runtime_get_sync(dev);
> @@ -142,40 +143,6 @@ static int cdns_ti_probe(struct platform_device *pdev)
>  		goto err;
>  	}
>  
> -	/* assert RESET */
> -	reg = cdns_ti_readl(data, USBSS_W1);
> -	reg &= ~USBSS_W1_PWRUP_RST;
> -	cdns_ti_writel(data, USBSS_W1, reg);
> -
> -	/* set static config */
> -	reg = cdns_ti_readl(data, USBSS_STATIC_CONFIG);
> -	reg &= ~USBSS1_STATIC_PLL_REF_SEL_MASK;
> -	reg |= rate_code << USBSS1_STATIC_PLL_REF_SEL_SHIFT;
> -
> -	reg &= ~USBSS1_STATIC_VBUS_SEL_MASK;
> -	data->vbus_divider = device_property_read_bool(dev, "ti,vbus-divider");
> -	if (data->vbus_divider)
> -		reg |= 1 << USBSS1_STATIC_VBUS_SEL_SHIFT;
> -
> -	cdns_ti_writel(data, USBSS_STATIC_CONFIG, reg);
> -	reg = cdns_ti_readl(data, USBSS_STATIC_CONFIG);
> -
> -	/* set USB2_ONLY mode if requested */
> -	reg = cdns_ti_readl(data, USBSS_W1);
> -	data->usb2_only = device_property_read_bool(dev, "ti,usb2-only");
> -	if (data->usb2_only)
> -		reg |= USBSS_W1_USB2_ONLY;
> -
> -	/* set default modestrap */
> -	reg |= USBSS_W1_MODESTRAP_SEL;
> -	reg &= ~USBSS_W1_MODESTRAP_MASK;
> -	reg |= USBSS_MODESTRAP_MODE_NONE << USBSS_W1_MODESTRAP_SHIFT;
> -	cdns_ti_writel(data, USBSS_W1, reg);
> -
> -	/* de-assert RESET */
> -	reg |= USBSS_W1_PWRUP_RST;
> -	cdns_ti_writel(data, USBSS_W1, reg);
> -
>  	error = of_platform_populate(node, NULL, NULL, dev);
>  	if (error) {
>  		dev_err(dev, "failed to create children: %d\n", error);
> @@ -211,6 +178,52 @@ static void cdns_ti_remove(struct platform_device *pdev)
>  	platform_set_drvdata(pdev, NULL);
>  }
>  
> +static int cdns_ti_runtime_resume(struct device *dev)
> +{
> +	struct cdns_ti *data = dev_get_drvdata(dev);
> +	u32 reg;
> +
> +	/* assert RESET */
> +	reg = cdns_ti_readl(data, USBSS_W1);
> +	reg &= ~USBSS_W1_PWRUP_RST;
> +	cdns_ti_writel(data, USBSS_W1, reg);
> +
> +	/* set static config */
> +	reg = cdns_ti_readl(data, USBSS_STATIC_CONFIG);
> +	reg &= ~USBSS1_STATIC_PLL_REF_SEL_MASK;
> +	reg |= data->usb2_refclk_rate_code << USBSS1_STATIC_PLL_REF_SEL_SHIFT;
> +
> +	reg &= ~USBSS1_STATIC_VBUS_SEL_MASK;
> +
> +	if (data->vbus_divider)
> +		reg |= 1 << USBSS1_STATIC_VBUS_SEL_SHIFT;
> +
> +	cdns_ti_writel(data, USBSS_STATIC_CONFIG, reg);
> +	reg = cdns_ti_readl(data, USBSS_STATIC_CONFIG);
> +
> +	/* set USB2_ONLY mode if requested */
> +	reg = cdns_ti_readl(data, USBSS_W1);
> +
> +	if (data->usb2_only)
> +		reg |= USBSS_W1_USB2_ONLY;
> +
> +	/* set default modestrap */
> +	reg |= USBSS_W1_MODESTRAP_SEL;
> +	reg &= ~USBSS_W1_MODESTRAP_MASK;
> +	reg |= USBSS_MODESTRAP_MODE_NONE << USBSS_W1_MODESTRAP_SHIFT;
> +	cdns_ti_writel(data, USBSS_W1, reg);
> +
> +	/* de-assert RESET */
> +	reg |= USBSS_W1_PWRUP_RST;
> +	cdns_ti_writel(data, USBSS_W1, reg);

I don't think USB controller requires a reset and re-init between runtime suspend/resume.

What you need is reset/re-init during system Resume on certain platforms.
So you should move this part of code into a helper function and call it
from .probe() and .system_resume()


> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops cdns_ti_pm_ops = {
> +	RUNTIME_PM_OPS(NULL, cdns_ti_runtime_resume, NULL)
> +};
> +
>  static const struct of_device_id cdns_ti_of_match[] = {
>  	{ .compatible = "ti,j721e-usb", },
>  	{ .compatible = "ti,am64-usb", },
> @@ -224,6 +237,7 @@ static struct platform_driver cdns_ti_driver = {
>  	.driver		= {
>  		.name	= "cdns3-ti",
>  		.of_match_table	= cdns_ti_of_match,
> +		.pm	= pm_ptr(&cdns_ti_pm_ops),
>  	},
>  };
>  
> 

-- 
cheers,
-roger