On 11/14/2011 11:39 AM, Takashi Iwai wrote:
OK, then perhaps a better fix is to change the check to be equivalent with pineview, as you mentioned in the original post. The handling of bit 0 for old chips was lost during the refactoring of backlight code since 2.6.37.
Does the patch below work for you?
The only concern by this fix is that it changes the max value. If apps expect some certain (e.g. recorded) value, it may screw up. But I don't expect this would happen with sane apps.
Works perfectly - let's ship it :)
Thanks again, Daniel
=== From: Takashi Iwai tiwai@suse.de Subject: drm/i915: Fix invalid backpanel values for GEN3 or older chips
While refactoring of backlight control code in commit [a95735569: drm/i915: Refactor panel backlight controls], the handling of the bit 0 of duty-cycle was gone except for pineview. This resulted in invalid register values for old chips like 915GM. When the bit 0 is set, the backlight is turned off suddenly.
This patch changes the bit-0 check by replacing with the condition of gen < 4 (pineview is included in this condition, too).
Reported-by: Daniel Mack zonque@gmail.com Signed-off-by: Takashi Iwai tiwai@suse.de
drivers/gpu/drm/i915/intel_panel.c | 8 +++----- 1 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index 499d4c0..737d00f 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -178,12 +178,10 @@ u32 intel_panel_get_max_backlight(struct drm_device *dev) if (HAS_PCH_SPLIT(dev)) { max >>= 16; } else {
if (IS_PINEVIEW(dev)) {
if (INTEL_INFO(dev)->gen < 4) { max >>= 17;
if (INTEL_INFO(dev)->gen < 4)max &= ~1;}
if (is_backlight_combination_mode(dev))
@@ -203,7 +201,7 @@ u32 intel_panel_get_backlight(struct drm_device *dev) val = I915_READ(BLC_PWM_CPU_CTL) & BACKLIGHT_DUTY_CYCLE_MASK; } else { val = I915_READ(BLC_PWM_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
if (IS_PINEVIEW(dev))
if (INTEL_INFO(dev)->gen < 4) val >>= 1;if (is_backlight_combination_mode(dev)) {
@@ -246,7 +244,7 @@ static void intel_panel_actually_set_backlight(struct drm_device *dev, u32 level }
tmp = I915_READ(BLC_PWM_CTL);
- if (IS_PINEVIEW(dev)) {
- if (INTEL_INFO(dev)->gen < 4) { tmp &= ~(BACKLIGHT_DUTY_CYCLE_MASK - 1); level <<= 1; } else