Re: [PATCH] backlight: initialize struct backlight_properties properly
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2012-05-22 20:59:06
Also in:
dri-devel, linux-omap, lkml, platform-driver-x86
On Mon, 21 May 2012 09:24:35 +0200 Corentin Chary [off-list ref] wrote:
quoted hunk ↗ jump to hunk
In all these files, the .power field was never correctly initialized. ...--- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c@@ -342,6 +342,7 @@ int intel_panel_setup_backlight(struct drm_device *dev) else return -ENODEV; + memset(&props, 0, sizeof(props));
This code is all still quite fragile. What happens if we add a new
field to backlight_properties? We need to go edit a zillion drivers?
There are two ways of fixing this:
a) write and use
void backlight_properties_init(struct backlight_properties *props,
int type, int max_brightness, etc);
or
b) edit all sites to do
struct backlight_properties bl_props = {
.type = BACKLIGHT_RAW,
.max_brighness = intel_panel_get_max_backlight(dev),
.power = FB_BLANK_UNBLANK,
};
they're largely equivalent - the struct will be zeroed out and
then certain fields will be initialised. a) is a bit better because
some future field may not want the all-zeroes pattern (eg, a spinlock).
But they're both better than what we have now!