linux-kernel - Re: [PATCH v2 tty-next 3/3] 8250: microchip: pci1xxxx: Add power management functions to quad-uart driver.

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Message-ID: <7892467b-c2de-c62-e977-62761dc5cbb@linux.intel.com>
Date:   Mon, 3 Oct 2022 12:51:23 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Kumaravel Thiagarajan <kumaravel.thiagarajan@...rochip.com>
cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>, andy.shevchenko@...il.com,
        u.kleine-koenig@...gutronix.de, johan@...nel.org,
        wander@...hat.com, etremblay@...tech-controls.com,
        macro@...am.me.uk, geert+renesas@...der.be, jk@...abs.org,
        phil.edworthy@...esas.com, Lukas Wunner <lukas@...ner.de>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-serial <linux-serial@...r.kernel.org>,
        UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH v2 tty-next 3/3] 8250: microchip: pci1xxxx: Add power
 management functions to quad-uart driver.

On Sat, 1 Oct 2022, Kumaravel Thiagarajan wrote:

> pci1xxxx's quad-uart function has the capability to wake up the host from
> suspend state. Enable wakeup before entering into suspend and disable
> wakeup on resume.
> 
> Signed-off-by: Kumaravel Thiagarajan <kumaravel.thiagarajan@...rochip.com>
> ---
> Changes in v2:
> - Use DEFINE_SIMPLE_DEV_PM_OPS instead of SIMPLE_DEV_PM_OPS.
> - Use pm_sleep_ptr instead of CONFIG_PM_SLEEP.
> - Change the return data type of pci1xxxx_port_suspend to bool from int.
> ---
>  drivers/tty/serial/8250/8250_pci1xxxx.c | 112 ++++++++++++++++++++++++
>  1 file changed, 112 insertions(+)
> 
> diff --git a/drivers/tty/serial/8250/8250_pci1xxxx.c b/drivers/tty/serial/8250/8250_pci1xxxx.c
> index 999e5a284266..0a0459f66177 100644
> --- a/drivers/tty/serial/8250/8250_pci1xxxx.c
> +++ b/drivers/tty/serial/8250/8250_pci1xxxx.c
> @@ -352,6 +352,112 @@ static void pci1xxxx_irq_assign(struct pci1xxxx_8250 *priv,
>  	}
>  }
>  
> +static bool pci1xxxx_port_suspend(int line)
> +{
> +	struct uart_8250_port *up = serial8250_get_port(line);
> +	struct uart_port *port = &up->port;
> +	unsigned long flags;
> +	u8 wakeup_mask;
> +	bool ret = false;
> +
> +	if (port->suspended == 0 && port->dev) {
> +		wakeup_mask = readb(up->port.membase + UART_WAKE_MASK_REG);
> +
> +		spin_lock_irqsave(&port->lock, flags);
> +		port->mctrl &= ~TIOCM_OUT2;
> +		port->ops->set_mctrl(port, port->mctrl);
> +		spin_unlock_irqrestore(&port->lock, flags);
> +
> +		if ((wakeup_mask & UART_WAKE_SRCS) != UART_WAKE_SRCS)
> +			ret = true;
> +	}
> +
> +	writeb(UART_WAKE_SRCS, port->membase + UART_WAKE_REG);
> +
> +	return ret;
> +}
> +
> +static void pci1xxxx_port_resume(int line)
> +{
> +	struct uart_8250_port *up = serial8250_get_port(line);
> +	struct uart_port *port = &up->port;
> +	unsigned long flags;
> +
> +	writeb(UART_WAKE_SRCS, port->membase + UART_WAKE_REG);
> +
> +	if (port->suspended == 0) {

Is this check the right way around?

> +		spin_lock_irqsave(&port->lock, flags);
> +		port->mctrl |= TIOCM_OUT2;
> +		port->ops->set_mctrl(port, port->mctrl);
> +		spin_unlock_irqrestore(&port->lock, flags);
> +	}
> +}
> +
> +static int pci1xxxx_suspend(struct device *dev)
> +{
> +	struct pci1xxxx_8250 *priv = dev_get_drvdata(dev);
> +	struct pci_dev *pcidev = to_pci_dev(dev);
> +	unsigned int data;
> +	void __iomem *p;
> +	bool wakeup = false;
> +	int i;
> +
> +	for (i = 0; i < priv->nr; i++) {
> +		if (priv->line[i] >= 0) {
> +			serial8250_suspend_port(priv->line[i]);
> +			wakeup |= pci1xxxx_port_suspend(priv->line[i]);

So first serial8250_suspend_port() calls into uart_suspend_port() that
sets port->suspended to 1, then pci1xxxx_port_suspend() checks if it's 0.
Is this intentional?


-- 
 i.