linux-kernel - Re: [PATCH 04/11] platform/x86: fujitsu-laptop: simplify set_lcd

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Date:   Mon, 3 Apr 2017 17:01:02 -0700
From:   Darren Hart <dvhart@...radead.org>
To:     Michał Kępień <kernel@...pniu.pl>
Cc:     Jonathan Woithe <jwoithe@...t42.net>,
        Andy Shevchenko <andy@...radead.org>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/11] platform/x86: fujitsu-laptop: simplify
 set_lcd_level()

On Thu, Mar 30, 2017 at 12:35:02PM +0200, Michał Kępień wrote:
> acpi_execute_simple_method() takes a method parameter which tells it to
> look for the given method underneath the given handle, so calling
> acpi_get_handle() beforehand is redundant.  Replace the call to
> acpi_get_handle() with a call to acpi_execute_simple_method(), thus
> eliminating the need for a local variable storing the handle.  Also do
> not assign a default value to status as it has no influence on execution
> flow.
> 
> Signed-off-by: Michał Kępień <kernel@...pniu.pl>
> ---
>  drivers/platform/x86/fujitsu-laptop.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/platform/x86/fujitsu-laptop.c b/drivers/platform/x86/fujitsu-laptop.c
> index 5005400b57bb..b888ba190fb2 100644
> --- a/drivers/platform/x86/fujitsu-laptop.c
> +++ b/drivers/platform/x86/fujitsu-laptop.c
> @@ -358,8 +358,7 @@ static enum led_brightness eco_led_get(struct led_classdev *cdev)
>  
>  static int set_lcd_level(int level)
>  {
> -	acpi_status status = AE_OK;
> -	acpi_handle handle = NULL;
> +	acpi_status status;
>  	char *method;
>  
>  	switch (use_alt_lcd_levels) {
> @@ -377,16 +376,13 @@ static int set_lcd_level(int level)
>  	if (level < 0 || level >= fujitsu_bl->max_brightness)
>  		return -EINVAL;
>  
> -	status = acpi_get_handle(fujitsu_bl->acpi_handle, method, &handle);
> +	status = acpi_execute_simple_method(fujitsu_bl->acpi_handle, method,
> +					    level);
>  	if (ACPI_FAILURE(status)) {
>  		vdbg_printk(FUJLAPTOP_DBG_ERROR, "%s not present\n", method);

So this changes behavior a little bit for debug messages. Previously, this
message only triggered if acpi_get_handle failed, now it will trigger if the
method exists but fails, whereas that was silent previously (see below). I think
printing in either case is fine, but we should adjust the message to reflect the
new code flow.

>  		return -ENODEV;
>  	}
>  
> -	status = acpi_execute_simple_method(handle, NULL, level);
> -	if (ACPI_FAILURE(status))
> -		return -ENODEV;
> -
>  	return 0;
>  }
>  
> -- 
> 2.12.1
> 
> 

-- 
Darren Hart
VMware Open Source Technology Center