linux-kernel - Re: [PATCH 3/3] ACPI video: Fix applying indexed initial brightness value.

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Message-ID: <5142E04F.1010400@intel.com>
Date:	Fri, 15 Mar 2013 16:48:15 +0800
From:	Aaron Lu <aaron.lu@...el.com>
To:	Danny Baumann <dannybaumann@....de>
CC:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Zhang Rui <rui.zhang@...el.com>, Len Brown <lenb@...nel.org>
Subject: Re: [PATCH 3/3] ACPI video: Fix applying indexed initial brightness
 value.

On 03/14/2013 06:34 PM, Danny Baumann wrote:
> The value initially read via _BQC also needs to be offset by 2 to
> compensate for the first 2 special items in _BCL. Introduce a helper
> function to do the conversion in order to not needlessly duplicate code.
> ---
>  drivers/acpi/video.c | 23 ++++++++++++++---------
>  1 file changed, 14 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
> index d0fade7..562ccc3 100644
> --- a/drivers/acpi/video.c
> +++ b/drivers/acpi/video.c
> @@ -450,6 +450,16 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
>  	{}
>  };
>  
> +static unsigned long long
> +acpi_video_index_to_level(struct acpi_video_device *device,
> +			  unsigned long long index)
> +{
> +	if (device->brightness->flags._BCL_reversed)
> +		index = device->brightness->count - 3 - index;
> +
> +	return device->brightness->levels[index + 2];
> +}

What about making this function also take care of the
bqc_offset_aml_bug_workaround? so that this function serves more like a
conversion from raw value to fixed value, the function name can perhaps
be named as: acpi_video_fix_bqc_value, or whatever you think is more
appropriate.

> +
>  static int
>  acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
>  					unsigned long long *level, int init)
> @@ -472,13 +482,10 @@ acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
>  				return 0;
>  			}
>  
> -			if (device->brightness->flags._BQC_use_index) {
> -				if (device->brightness->flags._BCL_reversed)
> -					*level = device->brightness->count
> -								 - 3 - (*level);
> -				*level = device->brightness->levels[*level + 2];
> +			if (device->brightness->flags._BQC_use_index)
> +				*level = acpi_video_index_to_level(device,
> +								   *level);
>  
> -			}
>  			*level += bqc_offset_aml_bug_workaround;
>  			for (i = 2; i < device->brightness->count; i++)
>  				if (device->brightness->levels[i] == *level) {
> @@ -742,9 +749,7 @@ acpi_video_init_brightness(struct acpi_video_device *device)
>  				}
>  		}
>  	} else {
> -		if (br->flags._BCL_reversed)
> -			level_old = (br->count - 1) - level_old;
> -		level = br->levels[level_old];
> +		level = acpi_video_index_to_level(device, level_old);

And here, that new function should be used, which also takes care of the
offset_aml_bug problem(though in theory, the two problems may not happen
on the same BIOS table).

And the acpi_video_device_lcd_get_level_current's param init can
probably be renamed as raw, meaning if raw value is desired or fixed
value, but it's not a big deal.

Thanks,
Aaron

>  	}
>  
>  set_level:
> 

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