Re: [PATCH 10/10] usb: host: xhci-tegra: Implement basic ELPG support

[Thierry Reding <thierry.reding@gmail.com>]

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On Tue, Nov 26, 2019 at 05:43:15PM +0200, Mathias Nyman wrote:
> On 25.11.2019 14.32, Thierry Reding wrote:
> > From: Thierry Reding <treding@nvidia.com>
> > 
> > This implements basic engine-level powergate support which allows the
> > XUSB controller to be put into a low power mode on system sleep and get
> > it out of that low power mode again on resume.
> > 
> > Based on work by JC Kuo <jckuo@nvidia.com>.
> > 
> > Signed-off-by: Thierry Reding <treding@nvidia.com>
> > ---
> >   drivers/usb/host/xhci-tegra.c | 137 ++++++++++++++++++++++++++++++++--
> >   1 file changed, 129 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
> > index cd3afec408ea..d0e30927a73f 100644
> > --- a/drivers/usb/host/xhci-tegra.c
> > +++ b/drivers/usb/host/xhci-tegra.c
> > @@ -1451,6 +1451,45 @@ static int tegra_xusb_remove(struct platform_device *pdev)
> >   }
> >   #ifdef CONFIG_PM_SLEEP
> > +static bool xhci_hub_ports_suspended(struct xhci_hub *hub)
> > +{
> > +	struct device *dev = hub->hcd->self.controller;
> > +	bool status = true;
> > +	unsigned int i;
> > +	u32 value;
> > +
> > +	for (i = 0; i < hub->num_ports; i++) {
> > +		value = readl(hub->ports[i]->addr);
> > +		if ((value & PORT_PE) == 0)
> > +			continue;
> > +
> > +		if ((value & PORT_PLS_MASK) != XDEV_U3) {
> > +			dev_info(dev, "%u-%u isn't suspended: %#010x\n",
> > +				 hub->hcd->self.busnum, i + 1, value);
> > +			status = false;
> > +		}
> > +	}
> > +
> > +	return status;
> > +}
> > +
> > +static int tegra_xusb_check_ports(struct tegra_xusb *tegra)
> > +{
> > +	struct xhci_hcd *xhci = hcd_to_xhci(tegra->hcd);
> > +	unsigned long flags;
> > +	int err = 0;
> > +
> > +	spin_lock_irqsave(&xhci->lock, flags);
> > +
> > +	if (!xhci_hub_ports_suspended(&xhci->usb2_rhub) ||
> > +	    !xhci_hub_ports_suspended(&xhci->usb3_rhub))
> > +		err = -EBUSY;
> > +
> > +	spin_unlock_irqrestore(&xhci->lock, flags);
> > +
> > +	return err;
> > +}
> > +
> >   static void tegra_xusb_save_context(struct tegra_xusb *tegra)
> >   {
> >   	const struct tegra_xusb_context_soc *soc = tegra->soc->context;
> > @@ -1485,31 +1524,113 @@ static void tegra_xusb_restore_context(struct tegra_xusb *tegra)
> >   	}
> >   }
> > -static int tegra_xusb_suspend(struct device *dev)
> > +static int tegra_xusb_enter_elpg(struct tegra_xusb *tegra, bool wakeup)
> >   {
> > -	struct tegra_xusb *tegra = dev_get_drvdata(dev);
> >   	struct xhci_hcd *xhci = hcd_to_xhci(tegra->hcd);
> > -	bool wakeup = device_may_wakeup(dev);
> > +	u32 value;
> >   	int err;
> > -	/* TODO: Powergate controller across suspend/resume. */
> > +	err = tegra_xusb_check_ports(tegra);
> > +	if (err < 0) {
> > +		dev_err(tegra->dev, "not all ports suspended: %d\n", err);
> > +		return err;
> > +	}
> > +
> >   	err = xhci_suspend(xhci, wakeup);
> > -	if (err < 0)
> > +	if (err < 0) {
> > +		dev_err(tegra->dev, "failed to suspend XHCI: %d\n", err);
> >   		return err;
> > +	}
> >   	tegra_xusb_save_context(tegra);
> > +	tegra_xusb_phy_disable(tegra);
> > +	tegra_xusb_clk_disable(tegra);
> >   	return 0;
> >   }
> > -static int tegra_xusb_resume(struct device *dev)
> > +static int tegra_xusb_exit_elpg(struct tegra_xusb *tegra, bool wakeup)
> >   {
> > -	struct tegra_xusb *tegra = dev_get_drvdata(dev);
> >   	struct xhci_hcd *xhci = hcd_to_xhci(tegra->hcd);
> > +	u32 value;
> > +	int err;
> > +	err = tegra_xusb_clk_enable(tegra);
> > +	if (err < 0) {
> > +		dev_err(tegra->dev, "failed to enable clocks: %d\n", err);
> > +		return err;
> > +	}
> > +
> > +	err = tegra_xusb_phy_enable(tegra);
> > +	if (err < 0) {
> > +		dev_err(tegra->dev, "failed to enable PHYs: %d\n", err);
> > +		goto disable_clk;
> > +	}
> > +
> > +	tegra_xusb_config(tegra);
> >   	tegra_xusb_restore_context(tegra);
> > -	return xhci_resume(xhci, false);
> > +	err = tegra_xusb_load_firmware(tegra);
> > +	if (err < 0) {
> > +		dev_err(tegra->dev, "failed to load firmware: %d\n", err);
> > +		goto disable_phy;
> > +	}
> > +
> > +	err = __tegra_xusb_enable_firmware_messages(tegra);
> > +	if (err < 0) {
> > +		dev_err(tegra->dev, "failed to enable messages: %d\n", err);
> > +		goto disable_phy;
> > +	}
> > +
> > +	err = xhci_resume(xhci, true);
> > +	if (err < 0) {
> > +		dev_err(tegra->dev, "failed to resume XHCI: %d\n", err);
> > +		goto disable_phy;
> > +	}
> > +
> > +	return 0;
> > +
> > +disable_phy:
> > +	tegra_xusb_phy_disable(tegra);
> > +disable_clk:
> > +	tegra_xusb_clk_disable(tegra);
> > +	return err;
> > +}
> > +
> > +static int tegra_xusb_suspend(struct device *dev)
> > +{
> > +	struct tegra_xusb *tegra = dev_get_drvdata(dev);
> > +	bool wakeup = device_may_wakeup(dev);
> > +	int err;
> > +
> > +	synchronize_irq(tegra->mbox_irq);
> > +
> > +	mutex_lock(&tegra->lock);
> > +
> > +	err = tegra_xusb_enter_elpg(tegra, wakeup);
> > +	if (err < 0)
> > +		goto unlock;
> 
> Is there some code missing here, or just preparing for some future feature?

This is just leftover I forgot to cleanup after I removed debug printk's
here. There's likely going to be some changes around this for better
runtime PM support, but that will all live in tegra_xusb_enter_elpg(),
so I think we can skip this. I've sent out a v2 with this...

> 
> > +
> > +unlock:
> > +	mutex_unlock(&tegra->lock);
> > +	return err;
> > +}
> > +
> > +static int tegra_xusb_resume(struct device *dev)
> > +{
> > +	struct tegra_xusb *tegra = dev_get_drvdata(dev);
> > +	bool wakeup = device_may_wakeup(dev);
> > +	int err;
> > +
> > +	mutex_lock(&tegra->lock);
> > +
> > +	err = tegra_xusb_exit_elpg(tegra, wakeup);
> > +	if (err < 0)
> > +		goto unlock;
> > +
> > +unlock:
> > +	mutex_unlock(&tegra->lock);
> > +	return err;
> >   }
> >   #endif

... and this fixed.

Thierry

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