Re: [PATCH v5] can: c_can: Add runtime PM support to Bosch C_CAN/D_CAN controller

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 08/07/2012 01:20 PM, AnilKumar Ch wrote:
> Add Runtime PM support to C_CAN/D_CAN controller. The runtime PM
> APIs control clocks for C_CAN/D_CAN IP and prevent access to the
> register of C_CAN/D_CAN IP when clock is turned off.
> 
> Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
> ---
> This patch has been tested on AM335X EVM. Due to lack of hardware
> I am not able to test c_can functionality. I appreciate if anyone
> can test c_can functionality with this patch.

The "priv->pdev->dev" will not work for c_can/d_can which are not using
the platform driver. Options:
a) priv->dev
   add a struct device pointer to the priv, and
   1) guard pm_runtime_get_sync() for priv->dev == NULL
      (or check if pm_runtime_get_sync copes with NULL pointer)

   - or -

   2) fill in the priv->dev in all other drivers (i.e. PCI)
      and check if it makes sense/works to call it on PCI hardware

b) convert all other drivers, i.e. the PCI driver to create a
   platform device

Without thinking long, I suggest to a) with flavour 1)

Maybe there are better solutions.

Marc

More comments inline:

> 
> This patch is based on "can-next/master" 
> 
> Changes from v4:
> 	- Incorporated Vaibhav H review comments on v4.
> 	  * Moved pm_runtime put/get_sync calls to appropriate positions.
> 	- This patch is from "Add DT support to C_CAN/D_CAN controller"
> 	  patch series. Rest of the patches in this series were applied
> 	  so this v5 contains only this patch.
> 
>  drivers/net/can/c_can/c_can.c          |    8 ++++++++
>  drivers/net/can/c_can/c_can.h          |    1 +
>  drivers/net/can/c_can/c_can_platform.c |   11 +++++++++++
>  3 files changed, 20 insertions(+)
> 
> diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
> index eea6608..ca1151d 100644
> --- a/drivers/net/can/c_can/c_can.c
> +++ b/drivers/net/can/c_can/c_can.c
> @@ -34,6 +34,8 @@
>  #include <linux/if_ether.h>
>  #include <linux/list.h>
>  #include <linux/io.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/platform_device.h>
>  
>  #include <linux/can.h>
>  #include <linux/can/dev.h>
> @@ -673,6 +675,8 @@ static int c_can_get_berr_counter(const struct net_device *dev,
>  	unsigned int reg_err_counter;
>  	struct c_can_priv *priv = netdev_priv(dev);
>  
> +	pm_runtime_get_sync(&priv->pdev->dev);
> +

Why do you make a get_sync() here, where's the correspondning put_sync()?

>  	reg_err_counter = priv->read_reg(priv, C_CAN_ERR_CNT_REG);
>  	bec->rxerr = (reg_err_counter & ERR_CNT_REC_MASK) >>
>  				ERR_CNT_REC_SHIFT;
> @@ -1053,6 +1057,8 @@ static int c_can_open(struct net_device *dev)
>  	int err;
>  	struct c_can_priv *priv = netdev_priv(dev);
>  
> +	pm_runtime_get_sync(&priv->pdev->dev);
> +
>  	/* open the can device */
>  	err = open_candev(dev);
>  	if (err) {

What if open_candev() fails? Please add a jump label
exit_open_candev_fail and add thje put_sync() there.

		goto exit_open_candev_fail;

> @@ -1079,6 +1085,7 @@ static int c_can_open(struct net_device *dev)
>  
>  exit_irq_fail:
>  	close_candev(dev);
 exit_open_candev_fail:
> +	pm_runtime_put_sync(&priv->pdev->dev);
>  	return err;
>  }
>  
> @@ -1091,6 +1098,7 @@ static int c_can_close(struct net_device *dev)
>  	c_can_stop(dev);
>  	free_irq(dev->irq, dev);
>  	close_candev(dev);
> +	pm_runtime_put_sync(&priv->pdev->dev);
>  
>  	return 0;
>  }
> diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
> index 4e56baa..ef84439 100644
> --- a/drivers/net/can/c_can/c_can.h
> +++ b/drivers/net/can/c_can/c_can.h
> @@ -153,6 +153,7 @@ struct c_can_priv {
>  	struct can_priv can;	/* must be the first member */
>  	struct napi_struct napi;
>  	struct net_device *dev;
> +	struct platform_device *pdev;
>  	int tx_object;
>  	int current_status;
>  	int last_status;
> diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
> index d0a66cf..cbb1184 100644
> --- a/drivers/net/can/c_can/c_can_platform.c
> +++ b/drivers/net/can/c_can/c_can_platform.c
> @@ -32,6 +32,7 @@
>  #include <linux/clk.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/pm_runtime.h>
>  
>  #include <linux/can/dev.h>
>  
> @@ -177,7 +178,11 @@ static int __devinit c_can_plat_probe(struct platform_device *pdev)
>  		goto exit_free_device;
>  	}
>  
> +	pm_runtime_enable(&pdev->dev);
> +	pm_runtime_get_sync(&pdev->dev);
> +
>  	dev->irq = irq;
> +	priv->pdev = pdev;
>  	priv->base = addr;
>  	priv->can.clock.freq = clk_get_rate(clk);
>  	priv->priv = clk;
> @@ -192,12 +197,16 @@ static int __devinit c_can_plat_probe(struct platform_device *pdev)
>  		goto exit_free_device;
>  	}
>  
> +	pm_runtime_put_sync(&pdev->dev);
> +
>  	dev_info(&pdev->dev, "%s device registered (regs=%p, irq=%d)\n",
>  		 KBUILD_MODNAME, priv->base, dev->irq);
>  	return 0;
>  
>  exit_free_device:
>  	platform_set_drvdata(pdev, NULL);
> +	pm_runtime_put_sync(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);
>  	free_c_can_dev(dev);
>  exit_iounmap:
>  	iounmap(addr);
> @@ -226,6 +235,8 @@ static int __devexit c_can_plat_remove(struct platform_device *pdev)
>  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	release_mem_region(mem->start, resource_size(mem));
>  
> +	pm_runtime_put_sync(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);
>  	clk_put(priv->priv);
>  
>  	return 0;
> 


-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
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