Date:	Sun, 11 Jan 2015 05:34:21 +0000
From:	Appana Durga Kedareswara Rao <appana.durga.rao@...inx.com>
To:	Marc Kleine-Budde <mkl@...gutronix.de>
CC:	"linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Soren Brinkmann" <sorenb@...inx.com>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"wg@...ndegger.com" <wg@...ndegger.com>
Subject: RE: [PATCH v4] can: Convert to runtime_pm

Hi Marc,

> -----Original Message-----
> From: Marc Kleine-Budde [mailto:mkl@...gutronix.de]
> Sent: Wednesday, January 07, 2015 5:59 PM
> To: Appana Durga Kedareswara Rao; wg@...ndegger.com; Michal Simek;
> grant.likely@...aro.org
> Cc: linux-can@...r.kernel.org; netdev@...r.kernel.org; linux-
> kernel@...r.kernel.org; Appana Durga Kedareswara Rao; Soren Brinkmann
> Subject: Re: [PATCH v4] can: Convert to runtime_pm
>
> On 12/23/2014 01:25 PM, Kedareswara rao Appana wrote:
> > Instead of enabling/disabling clocks at several locations in the
> > driver, use the runtime_pm framework. This consolidates the actions
> > for runtime PM in the appropriate callbacks and makes the driver more
> > readable and mantainable.
> >
> > Signed-off-by: Soren Brinkmann <soren.brinkmann@...inx.com>
> > Signed-off-by: Kedareswara rao Appana <appanad@...inx.com>
> > ---
> > Chnages for v4:
> >  - Updated with the review comments.
> > Changes for v3:
> >   - Converted the driver to use runtime_pm.
> > Changes for v2:
> >   - Removed the struct platform_device* from suspend/resume
> >     as suggest by Lothar.
> >
> >  drivers/net/can/xilinx_can.c |  123
> > +++++++++++++++++++++++++-----------------
> >  1 files changed, 74 insertions(+), 49 deletions(-)
> >
> > diff --git a/drivers/net/can/xilinx_can.c
> > b/drivers/net/can/xilinx_can.c index 6c67643..c71f683 100644
> > --- a/drivers/net/can/xilinx_can.c
> > +++ b/drivers/net/can/xilinx_can.c
> > @@ -32,6 +32,7 @@
> >  #include <linux/can/dev.h>
> >  #include <linux/can/error.h>
> >  #include <linux/can/led.h>
> > +#include <linux/pm_runtime.h>
> >
> >  #define DRIVER_NAME        "xilinx_can"
> >
> > @@ -138,7 +139,7 @@ struct xcan_priv {
> >     u32 (*read_reg)(const struct xcan_priv *priv, enum xcan_reg reg);
> >     void (*write_reg)(const struct xcan_priv *priv, enum xcan_reg reg,
> >                     u32 val);
> > -   struct net_device *dev;
> > +   struct device *dev;
> >     void __iomem *reg_base;
> >     unsigned long irq_flags;
> >     struct clk *bus_clk;
> > @@ -842,6 +843,13 @@ static int xcan_open(struct net_device *ndev)
> >     struct xcan_priv *priv = netdev_priv(ndev);
> >     int ret;
> >
> > +   ret = pm_runtime_get_sync(priv->dev);
> > +   if (ret < 0) {
> > +           netdev_err(ndev, "%s: pm_runtime_get failed\r(%d)\n\r",
> > +                           __func__, ret);
> > +           return ret;
> > +   }
> > +
> >     ret = request_irq(ndev->irq, xcan_interrupt, priv->irq_flags,
> >                     ndev->name, ndev);
> >     if (ret < 0) {
> > @@ -849,29 +857,17 @@ static int xcan_open(struct net_device *ndev)
> >             goto err;
> >     }
> >
> > -   ret = clk_prepare_enable(priv->can_clk);
> > -   if (ret) {
> > -           netdev_err(ndev, "unable to enable device clock\n");
> > -           goto err_irq;
> > -   }
> > -
> > -   ret = clk_prepare_enable(priv->bus_clk);
> > -   if (ret) {
> > -           netdev_err(ndev, "unable to enable bus clock\n");
> > -           goto err_can_clk;
> > -   }
> > -
> >     /* Set chip into reset mode */
> >     ret = set_reset_mode(ndev);
> >     if (ret < 0) {
> >             netdev_err(ndev, "mode resetting failed!\n");
> > -           goto err_bus_clk;
> > +           goto err_irq;
> >     }
> >
> >     /* Common open */
> >     ret = open_candev(ndev);
> >     if (ret)
> > -           goto err_bus_clk;
> > +           goto err_irq;
> >
> >     ret = xcan_chip_start(ndev);
> >     if (ret < 0) {
> > @@ -887,13 +883,11 @@ static int xcan_open(struct net_device *ndev)
> >
> >  err_candev:
> >     close_candev(ndev);
> > -err_bus_clk:
> > -   clk_disable_unprepare(priv->bus_clk);
> > -err_can_clk:
> > -   clk_disable_unprepare(priv->can_clk);
> >  err_irq:
> >     free_irq(ndev->irq, ndev);
> >  err:
> > +   pm_runtime_put(priv->dev);
> > +
> >     return ret;
> >  }
> >
> > @@ -910,12 +904,11 @@ static int xcan_close(struct net_device *ndev)
> >     netif_stop_queue(ndev);
> >     napi_disable(&priv->napi);
> >     xcan_chip_stop(ndev);
> > -   clk_disable_unprepare(priv->bus_clk);
> > -   clk_disable_unprepare(priv->can_clk);
> >     free_irq(ndev->irq, ndev);
> >     close_candev(ndev);
> >
> >     can_led_event(ndev, CAN_LED_EVENT_STOP);
> > +   pm_runtime_put(priv->dev);
> >
> >     return 0;
> >  }
> > @@ -934,27 +927,20 @@ static int xcan_get_berr_counter(const struct
> net_device *ndev,
> >     struct xcan_priv *priv = netdev_priv(ndev);
> >     int ret;
> >
> > -   ret = clk_prepare_enable(priv->can_clk);
> > -   if (ret)
> > -           goto err;
> > -
> > -   ret = clk_prepare_enable(priv->bus_clk);
> > -   if (ret)
> > -           goto err_clk;
> > +   ret = pm_runtime_get_sync(priv->dev);
> > +   if (ret < 0) {
> > +           netdev_err(ndev, "%s: pm_runtime_get failed\r(%d)\n\r",
> > +                           __func__, ret);
>
> Please remove the \r from the error messages.
>

Ok

> > +           return ret;
> > +   }
> >
> >     bec->txerr = priv->read_reg(priv, XCAN_ECR_OFFSET) &
> XCAN_ECR_TEC_MASK;
> >     bec->rxerr = ((priv->read_reg(priv, XCAN_ECR_OFFSET) &
> >                     XCAN_ECR_REC_MASK) >> XCAN_ESR_REC_SHIFT);
> >
> > -   clk_disable_unprepare(priv->bus_clk);
> > -   clk_disable_unprepare(priv->can_clk);
> > +   pm_runtime_put(priv->dev);
> >
> >     return 0;
> > -
> > -err_clk:
> > -   clk_disable_unprepare(priv->can_clk);
> > -err:
> > -   return ret;
> >  }
> >
> >
> > @@ -967,15 +953,45 @@ static const struct net_device_ops
> > xcan_netdev_ops = {
> >
> >  /**
> >   * xcan_suspend - Suspend method for the driver
> > - * @dev:   Address of the platform_device structure
> > + * @dev:   Address of the device structure
> >   *
> >   * Put the driver into low power mode.
> > - * Return: 0 always
> > + * Return: 0 on success and failure value on error
> >   */
> >  static int __maybe_unused xcan_suspend(struct device *dev)  {
> > -   struct platform_device *pdev = dev_get_drvdata(dev);
> > -   struct net_device *ndev = platform_get_drvdata(pdev);
> > +   if (!device_may_wakeup(dev))
> > +           return pm_runtime_force_suspend(dev);
> > +
> > +   return 0;
> > +}
> > +
> > +/**
> > + * xcan_resume - Resume from suspend
> > + * @dev:   Address of the device structure
> > + *
> > + * Resume operation after suspend.
> > + * Return: 0 on success and failure value on error  */ static int
> > +__maybe_unused xcan_resume(struct device *dev) {
> > +   if (!device_may_wakeup(dev))
> > +           return pm_runtime_force_resume(dev);
> > +
> > +   return 0;
> > +
> > +}
> > +
> > +/**
> > + * xcan_runtime_suspend - Runtime suspend method for the driver
> > + * @dev:   Address of the device structure
> > + *
> > + * Put the driver into low power mode.
> > + * Return: 0 always
> > + */
> > +static int __maybe_unused xcan_runtime_suspend(struct device *dev) {
> > +   struct net_device *ndev = dev_get_drvdata(dev);
> >     struct xcan_priv *priv = netdev_priv(ndev);
> >
> >     if (netif_running(ndev)) {
> > @@ -993,16 +1009,15 @@ static int __maybe_unused xcan_suspend(struct
> > device *dev)  }
> >
> >  /**
> > - * xcan_resume - Resume from suspend
> > - * @dev:   Address of the platformdevice structure
> > + * xcan_runtime_resume - Runtime resume from suspend
> > + * @dev:   Address of the device structure
> >   *
> >   * Resume operation after suspend.
> >   * Return: 0 on success and failure value on error
> >   */
> > -static int __maybe_unused xcan_resume(struct device *dev)
> > +static int __maybe_unused xcan_runtime_resume(struct device *dev)
> >  {
> > -   struct platform_device *pdev = dev_get_drvdata(dev);
> > -   struct net_device *ndev = platform_get_drvdata(pdev);
> > +   struct net_device *ndev = dev_get_drvdata(dev);
> >     struct xcan_priv *priv = netdev_priv(ndev);
> >     int ret;
>
> Some more context:
>
> >     ret = clk_enable(priv->bus_clk);
> >     if (ret) {
> >             dev_err(dev, "Cannot enable clock.\n");
> >             return ret;
> >     }
> >     ret = clk_enable(priv->can_clk);
> >     if (ret) {
> >             dev_err(dev, "Cannot enable clock.\n");
> >             clk_disable_unprepare(priv->bus_clk);
>
> This disable_unprepare looks wrong, should be a disable only.
>

Ok

> >             return ret;
> >     }
> >
> >     priv->write_reg(priv, XCAN_MSR_OFFSET, 0);
> >     priv->write_reg(priv, XCAN_SRR_OFFSET, XCAN_SRR_CEN_MASK);
> >
> >     if (netif_running(ndev)) {
> >             priv->can.state = CAN_STATE_ERROR_ACTIVE;
>
> What happens if the device was not in ACTIVE state prior to the
> runtime_suspend?
>

I am not sure about the state of CAN at this point of time.
I just followed what other drivers are following for run time  suspend :).

> >             netif_device_attach(ndev);
> >             netif_start_queue(ndev);
> >     }
> >
> >     return 0;
> > }
>
>
> >
> > @@ -1020,9 +1035,9 @@ static int __maybe_unused xcan_resume(struct
> > device *dev)
> >
> >     priv->write_reg(priv, XCAN_MSR_OFFSET, 0);
> >     priv->write_reg(priv, XCAN_SRR_OFFSET, XCAN_SRR_CEN_MASK);
> > -   priv->can.state = CAN_STATE_ERROR_ACTIVE;
> >
> >     if (netif_running(ndev)) {
> > +           priv->can.state = CAN_STATE_ERROR_ACTIVE;
> >             netif_device_attach(ndev);
> >             netif_start_queue(ndev);
> >     }
> > @@ -1030,7 +1045,10 @@ static int __maybe_unused xcan_resume(struct
> device *dev)
> >     return 0;
> >  }
> >
> > -static SIMPLE_DEV_PM_OPS(xcan_dev_pm_ops, xcan_suspend,
> xcan_resume);
> > +static const struct dev_pm_ops xcan_dev_pm_ops = {
> > +   SET_SYSTEM_SLEEP_PM_OPS(xcan_suspend, xcan_resume)
> > +   SET_PM_RUNTIME_PM_OPS(xcan_runtime_suspend,
> xcan_runtime_resume,
> > +NULL) };
> >
> >  /**
> >   * xcan_probe - Platform registration call @@ -1071,7 +1089,7 @@
> > static int xcan_probe(struct platform_device *pdev)
> >             return -ENOMEM;
> >
> >     priv = netdev_priv(ndev);
> > -   priv->dev = ndev;
> > +   priv->dev = &pdev->dev;
> >     priv->can.bittiming_const = &xcan_bittiming_const;
> >     priv->can.do_set_mode = xcan_do_set_mode;
> >     priv->can.do_get_berr_counter = xcan_get_berr_counter; @@ -
> 1137,15
> > +1155,22 @@ static int xcan_probe(struct platform_device *pdev)
> >
> >     netif_napi_add(ndev, &priv->napi, xcan_rx_poll, rx_max);
> >
> > +   pm_runtime_set_active(&pdev->dev);
> > +   pm_runtime_irq_safe(&pdev->dev);
> > +   pm_runtime_enable(&pdev->dev);
> > +   pm_runtime_get_sync(&pdev->dev);
> Check error values?

Ok
> > +
> >     ret = register_candev(ndev);
> >     if (ret) {
> >             dev_err(&pdev->dev, "fail to register failed (err=%d)\n",
> ret);
> > +           pm_runtime_put(priv->dev);
>
> Please move the pm_runtime_put into the common error exit path.
>

Ok

> >             goto err_unprepare_disable_busclk;
> >     }
> >
> >     devm_can_led_init(ndev);
> > -   clk_disable_unprepare(priv->bus_clk);
> > -   clk_disable_unprepare(priv->can_clk);
> > +
> > +   pm_runtime_put(&pdev->dev);
> > +
> >     netdev_dbg(ndev, "reg_base=0x%p irq=%d clock=%d, tx fifo
> depth:%d\n",
> >                     priv->reg_base, ndev->irq, priv->can.clock.freq,
> >                     priv->tx_max);
> >
>
> I think you have to convert the _remove() function, too. Have a look at the
> gpio-zynq.c driver:
>
> > static int zynq_gpio_remove(struct platform_device *pdev) {
> >     struct zynq_gpio *gpio = platform_get_drvdata(pdev);
> >
> >     pm_runtime_get_sync(&pdev->dev);
>
> However I don't understand why the get_sync() is here. Maybe Sören can
> help?

I converted the remove function to use the run-time PM and .
Below is the remove code snippet.

       ret = pm_runtime_get_sync(&pdev->dev);
        if (ret < 0) {
                netdev_err(ndev, "%s: pm_runtime_get failed(%d)\n",
                                __func__, ret);
                return ret;
        }

        if (set_reset_mode(ndev) < 0)
                netdev_err(ndev, "mode resetting failed!\n");

        unregister_candev(ndev);
        netif_napi_del(&priv->napi);
        free_candev(ndev);
        pm_runtime_disable(&pdev->dev);

Observed the below things in the /sys/kernel/debug/clk/clk_summary.

                                Modprobe        ifconfig up    ifconfig down   rmmod  Modprobe  ifconfig up   ifconfig down  rmmod  Modprobe  ifconfig up   ifconfig down  rmmod

Clk_prepare count:                         1                            1               1               1       2        2              2               2       3       3               3               3

Clk_enable count:                 0             1               0               1       2       2               2               2       3       3               3               3

Regards,
Kedar.

>
> >     gpiochip_remove(&gpio->chip);
> >     clk_disable_unprepare(gpio->clk);
> >     device_set_wakeup_capable(&pdev->dev, 0);
> >     return 0;
> > }
>
> regards,
> Marc
>
> --
> Pengutronix e.K.                  | Marc Kleine-Budde           |
> Industrial Linux Solutions        | Phone: +49-231-2826-924     |
> Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
> Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |



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