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Date: Wed, 7 Jan 2015 07:58:38 -0800
From: Sören Brinkmann <soren.brinkmann@...inx.com>
To: Marc Kleine-Budde <mkl@...gutronix.de>
CC: Kedareswara rao Appana <appana.durga.rao@...inx.com>,
<wg@...ndegger.com>, <michal.simek@...inx.com>,
<grant.likely@...aro.org>, <linux-can@...r.kernel.org>,
<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
Kedareswara rao Appana <appanad@...inx.com>
Subject: Re: [PATCH v4] can: Convert to runtime_pm
On Wed, 2015-01-07 at 01:28PM +0100, Marc Kleine-Budde wrote:
> 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.
>
> > + 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.
>
> > 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?
>
> > 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?
> > +
> > 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.
>
> > 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?
IIRC, the concern was that the remove function may be called while the device is
runtime suspended. Hence the remove function needs to resume the device since the
remove function may access the HW.
Sören
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