Re: [PATCH V3] can: flexcan: implement can Runtime PM

From: Marc Kleine-Budde
Date: Thu Nov 29 2018 - 04:44:13 EST

On 11/29/18 9:08 AM, Joakim Zhang wrote:
> From: Aisheng Dong <aisheng.dong@xxxxxxx>
>
> Flexcan will be disabled during suspend if no wakeup function required and
> enabled after resume accordingly. During this period, we could explicitly
> disable clocks.
> Since PM is optional, the clock is enabled at probe to guarante the
> clock is running when PM is not enabled in the kernel.
>
> Implement Runtime PM which will:
> 1) Without CONFIG_PM, clock is running whether Flexcan opened or closed.

ACK

> 2) With CONFIG_PM, clock enabled while Flexcan opened and disabled when

...when closed?

I think the sentence misses something at the end.

And it doesn't work:

> root@DistroKit:~ ifconfig can0
> can0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
> NOARP MTU:16 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:10
> RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
> Interrupt:34
>
> root@DistroKit:~ grep can /sys/kernel/debug/clk/clk_summary
> can_root 1 1 0 30000000 0 0 50000
> can2_serial 0 0 0 30000000 0 0 50000
> can1_serial 1 1 0 30000000 0 0 50000
> can2_ipg 0 0 0 66000000 0 0 50000
> can1_ipg 1 1 0 66000000 0 0 50000

can0 is down, while the can1_{serial,ipg} are enabled.

> 3) Regardless of CONFIG_PM enabled or not, Flexcan runtime status is
> SUSPENDED during Flexcan closed and ACTIVE when Flexcan opened.
> 4) Make Power Domain framework be able to shutdown the corresponding power
> domain of this device.
>
> Signed-off-by: Aisheng Dong <aisheng.dong@xxxxxxx>
> Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
> ---
> ChangeLog:
> V1->V2:
> *rebased on patch "can: flexcan: add self wakeup support".
> V2->V3:
> *fix device fails to probe without CONFIG_PM.
> ---
> drivers/net/can/flexcan.c | 107 +++++++++++++++++++++++++-------------
> 1 file changed, 70 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index 0f36eafe3ac1..cc62a97237db 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -24,6 +24,7 @@
> #include <linux/of.h>
> #include <linux/of_device.h>
> #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> #include <linux/regulator/consumer.h>
> #include <linux/regmap.h>
>
> @@ -277,6 +278,7 @@ struct flexcan_priv {
> u32 reg_imask1_default;
> u32 reg_imask2_default;
>
> + struct device *dev;
> struct clk *clk_ipg;
> struct clk *clk_per;
> const struct flexcan_devtype_data *devtype_data;
> @@ -444,6 +446,27 @@ static inline void flexcan_error_irq_disable(const struct flexcan_priv *priv)
> priv->write(reg_ctrl, &regs->ctrl);
> }
>
> +static int flexcan_clks_enable(const struct flexcan_priv *priv)
> +{
> + int err;
> +
> + err = clk_prepare_enable(priv->clk_ipg);
> + if (err)
> + return err;
> +
> + err = clk_prepare_enable(priv->clk_per);
> + if (err)
> + clk_disable_unprepare(priv->clk_ipg);
> +
> + return err;
> +}
> +
> +static void flexcan_clks_disable(const struct flexcan_priv *priv)
> +{
> + clk_disable_unprepare(priv->clk_ipg);
> + clk_disable_unprepare(priv->clk_per);
> +}
> +
> static inline int flexcan_transceiver_enable(const struct flexcan_priv *priv)
> {
> if (!priv->reg_xceiver)
> @@ -570,19 +593,13 @@ static int flexcan_get_berr_counter(const struct net_device *dev,
> const struct flexcan_priv *priv = netdev_priv(dev);
> int err;
>
> - err = clk_prepare_enable(priv->clk_ipg);
> - if (err)
> + err = pm_runtime_get_sync(priv->dev);
> + if (err < 0)
> return err;
>
> - err = clk_prepare_enable(priv->clk_per);
> - if (err)
> - goto out_disable_ipg;
> -
> err = __flexcan_get_berr_counter(dev, bec);
>
> - clk_disable_unprepare(priv->clk_per);
> - out_disable_ipg:
> - clk_disable_unprepare(priv->clk_ipg);
> + pm_runtime_put(priv->dev);
>
> return err;
> }
> @@ -1215,17 +1232,13 @@ static int flexcan_open(struct net_device *dev)
> struct flexcan_priv *priv = netdev_priv(dev);
> int err;
>
> - err = clk_prepare_enable(priv->clk_ipg);
> - if (err)
> + err = pm_runtime_get_sync(priv->dev);
> + if (err < 0)
> return err;
>
> - err = clk_prepare_enable(priv->clk_per);
> - if (err)
> - goto out_disable_ipg;
> -
> err = open_candev(dev);
> if (err)
> - goto out_disable_per;
> + goto out_disable_clks;
>
> err = request_irq(dev->irq, flexcan_irq, IRQF_SHARED, dev->name, dev);
> if (err)
> @@ -1288,10 +1301,8 @@ static int flexcan_open(struct net_device *dev)
> free_irq(dev->irq, dev);
> out_close:
> close_candev(dev);
> - out_disable_per:
> - clk_disable_unprepare(priv->clk_per);
> - out_disable_ipg:
> - clk_disable_unprepare(priv->clk_ipg);
> + out_disable_clks:
> + pm_runtime_put(priv->dev);
>
> return err;
> }
> @@ -1306,10 +1317,9 @@ static int flexcan_close(struct net_device *dev)
>
> can_rx_offload_del(&priv->offload);
> free_irq(dev->irq, dev);
> - clk_disable_unprepare(priv->clk_per);
> - clk_disable_unprepare(priv->clk_ipg);
>
> close_candev(dev);
> + pm_runtime_put(priv->dev);
>
> can_led_event(dev, CAN_LED_EVENT_STOP);
>
> @@ -1349,18 +1359,14 @@ static int register_flexcandev(struct net_device *dev)
> struct flexcan_regs __iomem *regs = priv->regs;
> u32 reg, err;
>
> - err = clk_prepare_enable(priv->clk_ipg);
> + err = flexcan_clks_enable(priv);
> if (err)
> return err;
>
> - err = clk_prepare_enable(priv->clk_per);
> - if (err)
> - goto out_disable_ipg;
> -
> /* select "bus clock", chip must be disabled */
> err = flexcan_chip_disable(priv);
> if (err)
> - goto out_disable_per;
> + goto out_disable_clks;
> reg = priv->read(&regs->ctrl);
> reg |= FLEXCAN_CTRL_CLK_SRC;
> priv->write(reg, &regs->ctrl);
> @@ -1389,13 +1395,12 @@ static int register_flexcandev(struct net_device *dev)
>
> err = register_candev(dev);
>
> - /* disable core and turn off clocks */

Please disable the device, even if keeping the clocks on.

> + return 0;
> +
> out_chip_disable:
> flexcan_chip_disable(priv);
> - out_disable_per:
> - clk_disable_unprepare(priv->clk_per);
> - out_disable_ipg:
> - clk_disable_unprepare(priv->clk_ipg);
> + out_disable_clks:
> + flexcan_clks_disable(priv);
>
> return err;
> }
> @@ -1556,6 +1561,7 @@ static int flexcan_probe(struct platform_device *pdev)
> priv->write = flexcan_write_le;
> }
>
> + priv->dev = &pdev->dev;
> priv->can.clock.freq = clock_freq;
> priv->can.bittiming_const = &flexcan_bittiming_const;
> priv->can.do_set_mode = flexcan_set_mode;
> @@ -1586,6 +1592,9 @@ static int flexcan_probe(struct platform_device *pdev)
> dev_info(&pdev->dev, "device registered (reg_base=%p, irq=%d)\n",
> priv->regs, dev->irq);
>
> + pm_runtime_enable(&pdev->dev);
> + pm_runtime_put(&pdev->dev);
> +
> return 0;
>
> failed_register:
> @@ -1598,6 +1607,7 @@ static int flexcan_remove(struct platform_device *pdev)
> struct net_device *dev = platform_get_drvdata(pdev);
>
> unregister_flexcandev(dev);
> + pm_runtime_disable(&pdev->dev);
> free_candev(dev);
>
> return 0;
> @@ -1607,7 +1617,7 @@ static int __maybe_unused flexcan_suspend(struct device *device)
> {
> struct net_device *dev = dev_get_drvdata(device);
> struct flexcan_priv *priv = netdev_priv(dev);
> - int err;
> + int err = 0;
>
> if (netif_running(dev)) {
> /* if wakeup is enabled, enter stop mode
> @@ -1620,20 +1630,22 @@ static int __maybe_unused flexcan_suspend(struct device *device)
> err = flexcan_chip_disable(priv);
> if (err)
> return err;
> +
> + err = pm_runtime_force_suspend(device);
> }
> netif_stop_queue(dev);
> netif_device_detach(dev);
> }
> priv->can.state = CAN_STATE_SLEEPING;
>
> - return 0;
> + return err;
> }
>
> static int __maybe_unused flexcan_resume(struct device *device)
> {
> struct net_device *dev = dev_get_drvdata(device);
> struct flexcan_priv *priv = netdev_priv(dev);
> - int err;
> + int err = 0;
>
> priv->can.state = CAN_STATE_ERROR_ACTIVE;
> if (netif_running(dev)) {
> @@ -1642,14 +1654,34 @@ static int __maybe_unused flexcan_resume(struct device *device)
> if (device_may_wakeup(device)) {
> disable_irq_wake(dev->irq);
> } else {
> - err = flexcan_chip_enable(priv);
> + err = pm_runtime_force_resume(device);
> if (err)
> return err;
> +
> + err = flexcan_chip_enable(priv);
> }
> }
> + return err;
> +}
> +
> +static int __maybe_unused flexcan_runtime_suspend(struct device *device)
> +{
> + struct net_device *dev = dev_get_drvdata(device);
> + struct flexcan_priv *priv = netdev_priv(dev);
> +
> + flexcan_clks_disable(priv);
> +
> return 0;
> }
>
> +static int __maybe_unused flexcan_runtime_resume(struct device *device)
> +{
> + struct net_device *dev = dev_get_drvdata(device);
> + struct flexcan_priv *priv = netdev_priv(dev);
> +
> + return flexcan_clks_enable(priv);
> +}
> +
> static int __maybe_unused flexcan_noirq_suspend(struct device *device)
> {
> struct net_device *dev = dev_get_drvdata(device);
> @@ -1676,6 +1708,7 @@ static int __maybe_unused flexcan_noirq_resume(struct device *device)
>
> static const struct dev_pm_ops flexcan_pm_ops = {
> SET_SYSTEM_SLEEP_PM_OPS(flexcan_suspend, flexcan_resume)
> + SET_RUNTIME_PM_OPS(flexcan_runtime_suspend, flexcan_runtime_resume, NULL)
> SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(flexcan_noirq_suspend, flexcan_noirq_resume)
> };
>
>

Marc

--
Pengutronix e.K. | Marc Kleine-Budde |
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