Re: [Xen-devel] [PATCH 18/44] mfd: twl4030-power: Register with kernel poweroff handler

[Lee Jones <lee.jones@xxxxxxxxxx>]

On Mon, 06 Oct 2014, Guenter Roeck wrote:

> Register with kernel poweroff handler instead of setting pm_power_off
> directly. Register with a low priority value of 64 to reflect that
> the original code only sets pm_power_off if it was not already set.
> 
> Make twl4030_power_off static as it is only called from the twl4030-power
> driver.
> 
> Cc: Samuel Ortiz <sameo@xxxxxxxxxxxxxxx>
> Cc: Lee Jones <lee.jones@xxxxxxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
>  drivers/mfd/twl4030-power.c | 25 +++++++++++++++++++++----
>  include/linux/i2c/twl.h     |  1 -
>  2 files changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mfd/twl4030-power.c b/drivers/mfd/twl4030-power.c
> index 4d3ff37..bd6b830 100644
> --- a/drivers/mfd/twl4030-power.c
> +++ b/drivers/mfd/twl4030-power.c
> @@ -25,9 +25,10 @@
>   */
>  
>  #include <linux/module.h>
> -#include <linux/pm.h>
> +#include <linux/notifier.h>
>  #include <linux/i2c/twl.h>
>  #include <linux/platform_device.h>
> +#include <linux/pm.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
>  
> @@ -611,7 +612,8 @@ twl4030_power_configure_resources(const struct 
> twl4030_power_data *pdata)
>   * After a successful execution, TWL shuts down the power to the SoC
>   * and all peripherals connected to it.
>   */
> -void twl4030_power_off(void)
> +static int twl4030_power_off(struct notifier_block *this, unsigned long 
> unused1,
> +                          void *unused2)
>  {
>       int err;
>  
> @@ -619,8 +621,15 @@ void twl4030_power_off(void)
>                              TWL4030_PM_MASTER_P1_SW_EVENTS);
>       if (err)
>               pr_err("TWL4030 Unable to power off\n");
> +
> +     return NOTIFY_DONE;
>  }
>  
> +static struct notifier_block twl4030_poweroff_nb = {
> +     .notifier_call = twl4030_power_off,
> +     .priority = 64,

64 out of what?  How is this calculated?  Wouldn't it be better to
define these?

> +};
> +
>  static bool twl4030_power_use_poweroff(const struct twl4030_power_data 
> *pdata,
>                                       struct device_node *node)
>  {
> @@ -836,7 +845,7 @@ static int twl4030_power_probe(struct platform_device 
> *pdev)
>       }
>  
>       /* Board has to be wired properly to use this feature */
> -     if (twl4030_power_use_poweroff(pdata, node) && !pm_power_off) {
> +     if (twl4030_power_use_poweroff(pdata, node)) {
>               /* Default for SEQ_OFFSYNC is set, lets ensure this */
>               err = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &val,
>                                     TWL4030_PM_MASTER_CFG_P123_TRANSITION);
> @@ -853,7 +862,13 @@ static int twl4030_power_probe(struct platform_device 
> *pdev)
>                       }
>               }
>  
> -             pm_power_off = twl4030_power_off;
> +             err = register_poweroff_handler(&twl4030_poweroff_nb);
> +             if (err) {
> +                     dev_err(&pdev->dev,
> +                             "Failed to register poweroff handler\n");

If this is not fatal, you should issue a dev_warn() instead.

> +                     /* Not a fatal error */
> +                     err = 0;

How about using your own variable for this?  Then you don't have to
worry about resetting it.

> +             }
>       }
>  
>  relock:
> @@ -869,6 +884,8 @@ relock:
>  
>  static int twl4030_power_remove(struct platform_device *pdev)
>  {
> +     unregister_poweroff_handler(&twl4030_poweroff_nb);

Perhaps a naive question, but is there any way you can do this using
devres (devm_* managed resources)?

>       return 0;
>  }
>  
> diff --git a/include/linux/i2c/twl.h b/include/linux/i2c/twl.h
> index 8cfb50f..f8544f1 100644
> --- a/include/linux/i2c/twl.h
> +++ b/include/linux/i2c/twl.h
> @@ -680,7 +680,6 @@ struct twl4030_power_data {
>  };
>  
>  extern int twl4030_remove_script(u8 flags);
> -extern void twl4030_power_off(void);
>  
>  struct twl4030_codec_data {
>       unsigned int digimic_delay; /* in ms */

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org â Open source software for ARM SoCs
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