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drm/i915: do not expose a dysfunctional backlight interface to userspace

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Previously intel_panel_setup_backlight() would create a sysfs backlight
interface with max brightness of 1 if it was unable to figure out the max
backlight brightness. This rendered the backlight interface useless.

Do not create a dysfunctional backlight interface to begin with.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Tested-by: David Woodhouse <David.Woodhouse@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Jani Nikula 2012-09-03 16:25:12 +03:00 committed by Daniel Vetter
parent fcbc50da77
commit 28dcc2d60c
1 changed files with 22 additions and 9 deletions
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31
drivers/gpu/drm/i915/intel_panel.c
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@ -162,19 +162,12 @@ static u32 i915_read_blc_pwm_ctl(struct drm_i915_private *dev_priv)
return val;
}
u32 intel_panel_get_max_backlight(struct drm_device *dev)
static u32 _intel_panel_get_max_backlight(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
u32 max;
max = i915_read_blc_pwm_ctl(dev_priv);
if (max == 0) {
/* XXX add code here to query mode clock or hardware clock
* and program max PWM appropriately.
*/
pr_warn_once("fixme: max PWM is zero\n");
return 1;
}
if (HAS_PCH_SPLIT(dev)) {
max >>= 16;
@ -188,6 +181,22 @@ u32 intel_panel_get_max_backlight(struct drm_device *dev)
max *= 0xff;
}
return max;
}
u32 intel_panel_get_max_backlight(struct drm_device *dev)
{
u32 max;
max = _intel_panel_get_max_backlight(dev);
if (max == 0) {
/* XXX add code here to query mode clock or hardware clock
* and program max PWM appropriately.
*/
pr_warn_once("fixme: max PWM is zero\n");
return 1;
}
DRM_DEBUG_DRIVER("max backlight PWM = %d\n", max);
return max;
}
@ -424,7 +433,11 @@ int intel_panel_setup_backlight(struct drm_device *dev)
memset(&props, 0, sizeof(props));
props.type = BACKLIGHT_RAW;
props.max_brightness = intel_panel_get_max_backlight(dev);
props.max_brightness = _intel_panel_get_max_backlight(dev);
if (props.max_brightness == 0) {
DRM_ERROR("Failed to get maximum backlight value\n");
return -ENODEV;
}
dev_priv->backlight =
backlight_device_register("intel_backlight",
&connector->kdev, dev,