Re: [PATCH 6/7] platform/x86: fujitsu-laptop: Define constants for backlight power control

From: Jonathan Woithe
Date: Fri Feb 16 2018 - 06:08:50 EST


On Sun, Feb 11, 2018 at 10:07:26PM +0100, Micha?? K??pie?? wrote:
> Use named constants instead of integers in call_fext_func() invocations
> related to backlight power control in order to more clearly convey the
> intent of each call.
>
> Signed-off-by: Micha?? K??pie?? <kernel@xxxxxxxxxx>
> ---
[cut]
> +/* FUNC interface - backlight power control */
> +#define BACKLIGHT_POWER 0x4
> +#define BACKLIGHT_OFF 0x3
> +#define BACKLIGHT_ON 0x0

A minor detail: BACKLIGHT_OFF and BACKLIGHT_ON are potential parameter
values while BACKLIGHT_POWER is essentially a parameter selector. Should
the name of BACKLIGHT_POWER reflect this difference? It could be difficult
to do without making the resulting identifier a little long. The best I can
come up with is BACKLIGHT_PARAM_POWER or (if a saving of one character is
desired) BACKLIGHT_PARM_POWER.

[cut]
> @@ -818,7 +825,8 @@ static int acpi_fujitsu_laptop_add(struct acpi_device *device)
> /* Sync backlight power status */
> if (fujitsu_bl && fujitsu_bl->bl_device &&
> acpi_video_get_backlight_type() == acpi_backlight_vendor) {
> - if (call_fext_func(fext, FUNC_BACKLIGHT, 0x2, 0x4, 0x0) == 3)
> + if (call_fext_func(fext, FUNC_BACKLIGHT, 0x2, BACKLIGHT_POWER,
> + 0x0) == 3)
> fujitsu_bl->bl_device->props.power = FB_BLANK_POWERDOWN;
> else
> fujitsu_bl->bl_device->props.power = FB_BLANK_UNBLANK;

I'm curious: this fext function call is, I think, returning the current
backlight power value. If that's the case, is the value of 3 used in the
test of the return function conceptually BACKLIGHT_OFF, and if so, should we
use BACKLIGHT_OFF instead of the numeric constant? It seems likely given
that it results in the backlight power property being set to
FB_BLANK_POWERDOWN.

Regards
jonathan