linux-kernel - Re: [PATCH 1/3] phy: usb: Leave some clocks running during suspend

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Message-ID: <YahNIinbEwB569C1@matsya>
Date:   Thu, 2 Dec 2021 10:05:46 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Al Cooper <alcooperx@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com,
        Florian Fainelli <f.fainelli@...il.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        linux-phy@...ts.infradead.org,
        Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH 1/3] phy: usb: Leave some clocks running during suspend

On 01-12-21, 13:06, Al Cooper wrote:
> The PHY client driver does a phy_exit() call on suspend or rmmod and
> the PHY driver needs to know the difference because some clocks need
> to be kept running for suspend but can be shutdown on unbind/rmmod
> (or if there are no PHY clients at all).
> 
> The fix is to use a PM notifier so the driver can tell if a PHY
> client is calling exit() because of a system suspend or a driver
> unbind/rmmod.
> 
> Signed-off-by: Al Cooper <alcooperx@...il.com>
> ---
>  drivers/phy/broadcom/phy-brcm-usb.c | 38 +++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/drivers/phy/broadcom/phy-brcm-usb.c b/drivers/phy/broadcom/phy-brcm-usb.c
> index 116fb23aebd9..0f1deb6e0eab 100644
> --- a/drivers/phy/broadcom/phy-brcm-usb.c
> +++ b/drivers/phy/broadcom/phy-brcm-usb.c
> @@ -18,6 +18,7 @@
>  #include <linux/soc/brcmstb/brcmstb.h>
>  #include <dt-bindings/phy/phy.h>
>  #include <linux/mfd/syscon.h>
> +#include <linux/suspend.h>
>  
>  #include "phy-brcm-usb-init.h"
>  
> @@ -70,12 +71,35 @@ struct brcm_usb_phy_data {
>  	int			init_count;
>  	int			wake_irq;
>  	struct brcm_usb_phy	phys[BRCM_USB_PHY_ID_MAX];
> +	struct notifier_block	pm_notifier;
> +	bool			pm_active;
>  };
>  
>  static s8 *node_reg_names[BRCM_REGS_MAX] = {
>  	"crtl", "xhci_ec", "xhci_gbl", "usb_phy", "usb_mdio", "bdc_ec"
>  };
>  
> +static int brcm_pm_notifier(struct notifier_block *notifier,
> +			    unsigned long pm_event,
> +			    void *unused)
> +{
> +	struct brcm_usb_phy_data *priv =
> +		container_of(notifier, struct brcm_usb_phy_data, pm_notifier);
> +
> +	switch (pm_event) {
> +	case PM_HIBERNATION_PREPARE:
> +	case PM_SUSPEND_PREPARE:
> +		priv->pm_active = true;
> +		break;
> +	case PM_POST_RESTORE:
> +	case PM_POST_HIBERNATION:
> +	case PM_POST_SUSPEND:
> +		priv->pm_active = false;
> +		break;
> +	}
> +	return NOTIFY_DONE;
> +}
> +
>  static irqreturn_t brcm_usb_phy_wake_isr(int irq, void *dev_id)
>  {
>  	struct phy *gphy = dev_id;
> @@ -91,6 +115,9 @@ static int brcm_usb_phy_init(struct phy *gphy)
>  	struct brcm_usb_phy_data *priv =
>  		container_of(phy, struct brcm_usb_phy_data, phys[phy->id]);
>  
> +	if (priv->pm_active)
> +		return 0;
> +
>  	/*
>  	 * Use a lock to make sure a second caller waits until
>  	 * the base phy is inited before using it.
> @@ -120,6 +147,9 @@ static int brcm_usb_phy_exit(struct phy *gphy)
>  	struct brcm_usb_phy_data *priv =
>  		container_of(phy, struct brcm_usb_phy_data, phys[phy->id]);
>  
> +	if (priv->pm_active)
> +		return 0;
> +
>  	dev_dbg(&gphy->dev, "EXIT\n");
>  	if (phy->id == BRCM_USB_PHY_2_0)
>  		brcm_usb_uninit_eohci(&priv->ini);
> @@ -488,6 +518,9 @@ static int brcm_usb_phy_probe(struct platform_device *pdev)
>  	if (err)
>  		return err;
>  
> +	priv->pm_notifier.notifier_call = brcm_pm_notifier;
> +	register_pm_notifier(&priv->pm_notifier);
> +
>  	mutex_init(&priv->mutex);
>  
>  	/* make sure invert settings are correct */
> @@ -528,7 +561,10 @@ static int brcm_usb_phy_probe(struct platform_device *pdev)
>  
>  static int brcm_usb_phy_remove(struct platform_device *pdev)
>  {
> +	struct brcm_usb_phy_data *priv = dev_get_drvdata(&pdev->dev);
> +
>  	sysfs_remove_group(&pdev->dev.kobj, &brcm_usb_phy_group);
> +	unregister_pm_notifier(&priv->pm_notifier);
>  
>  	return 0;
>  }
> @@ -539,6 +575,7 @@ static int brcm_usb_phy_suspend(struct device *dev)
>  	struct brcm_usb_phy_data *priv = dev_get_drvdata(dev);
>  
>  	if (priv->init_count) {
> +		dev_dbg(dev, "SUSPEND\n");

debug artifact?

>  		priv->ini.wake_enabled = device_may_wakeup(dev);
>  		if (priv->phys[BRCM_USB_PHY_3_0].inited)
>  			brcm_usb_uninit_xhci(&priv->ini);
> @@ -578,6 +615,7 @@ static int brcm_usb_phy_resume(struct device *dev)
>  	 * Uninitialize anything that wasn't previously initialized.
>  	 */
>  	if (priv->init_count) {
> +		dev_dbg(dev, "RESUME\n");

here too

>  		if (priv->wake_irq >= 0)
>  			disable_irq_wake(priv->wake_irq);
>  		brcm_usb_init_common(&priv->ini);
> -- 
> 2.17.1

-- 
~Vinod