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Date:	Mon, 12 Jan 2015 06:59:54 +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>,
	"Michal Simek" <michals@...inx.com>
Subject: RE: [PATCH v4] can: Convert to runtime_pm

Hi Marc,

> -----Original Message-----
> From: Marc Kleine-Budde [mailto:mkl@...gutronix.de]
> Sent: Sunday, January 11, 2015 9:11 PM
> To: Appana Durga Kedareswara Rao
> Cc: linux-can@...r.kernel.org; netdev@...r.kernel.org; linux-
> kernel@...r.kernel.org; Soren Brinkmann; grant.likely@...aro.org;
> wg@...ndegger.com
> Subject: Re: [PATCH v4] can: Convert to runtime_pm
>
> On 01/11/2015 06:34 AM, Appana Durga Kedareswara Rao wrote:
> [...]
> >>>             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 :).
>
> Please check the state of the hardware if you go with bus off into suspend
> and then resume.
>

        if (netif_running(ndev)) {
                        if (isr & XCAN_IXR_BSOFF_MASK) {
                                priv->can.state = CAN_STATE_BUS_OFF;
                           priv->write_reg(priv, XCAN_SRR_OFFSET,
                                        XCAN_SRR_RESET_MASK);
                } else if ((status & XCAN_SR_ESTAT_MASK) ==
                                        XCAN_SR_ESTAT_MASK) {
                        priv->can.state = CAN_STATE_ERROR_PASSIVE;
                } else if (status & XCAN_SR_ERRWRN_MASK) {
                        priv->can.state = CAN_STATE_ERROR_WARNING;
                } else {
                        priv->can.state = CAN_STATE_ERROR_ACTIVE;
                }
        }

Is the above code snippet ok for you?

> >>>             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);
>
> Can this make a call to xcan_runtime_*()? I'm asking since the ndev has
> been unregistered and already free()ed. Better move this directly after the
> set_reset_mode(). This way you are symmetric to the probe() function.

If I move the  pm_runtime_disable after the set_reset_mode
I am getting the below error.
ERROR:
xilinx_can e0008000.can can0 (unregistering): xcan_get_berr_counter: pm_runtime_get fail

If I move the pm_runtime_disable after unregister_candev everything is working fine.

Regards,
Kedar.

>
> > 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
>
> As the numbers are increasing you have a clk_prepare_enable() leak. Your
> remove() function is missing the clk_disable_unprepare() for the can and
> bus clock (as you have clk_prepare_enable in probe()).
>
> 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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