On lynxpoint the bios sometimes sets up the backlight using the CPU display, but the driver expects using the PWM PCH override register. Read the value from the CPU register, then convert it to the other units by converting from the old duty cycle, to freq, to the new units. This value is then programmed in the override register, after which we set the override and disable the CPU display control. This allows us to switch the source without flickering, and make the backlight controls work in the driver. Changes since v1: - Read BLC_PWM_CPU_CTL2 to cpu_ctl2. - Clean up cpu_mode if slightly. - Always disable BLM_PWM_ENABLE in cpu_ctl2. Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108225 Cc: Basil Eric Rabi <ericbasil.rabi@xxxxxxxxx> Cc: Hans de Goede <jwrdegoede@xxxxxxxxxxxxxxxxx> Cc: Tolga Cakir <cevelnet@xxxxxxxxx> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Tested-by: Tolga Cakir <cevelnet@xxxxxxxxx> --- drivers/gpu/drm/i915/intel_panel.c | 40 +++++++++++++++++++++++++++--- 1 file changed, 36 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index 799284fcd57d..3e3ce7a77700 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -1484,8 +1484,8 @@ static int lpt_setup_backlight(struct intel_connector *connector, enum pipe unus { struct drm_i915_private *dev_priv = to_i915(connector->base.dev); struct intel_panel *panel = &connector->panel; - u32 pch_ctl1, pch_ctl2, val; - bool alt; + u32 cpu_ctl2, pch_ctl1, pch_ctl2, val; + bool alt, cpu_mode; if (HAS_PCH_LPT(dev_priv)) alt = I915_READ(SOUTH_CHICKEN2) & LPT_PWM_GRANULARITY; @@ -1499,6 +1499,8 @@ static int lpt_setup_backlight(struct intel_connector *connector, enum pipe unus pch_ctl2 = I915_READ(BLC_PWM_PCH_CTL2); panel->backlight.max = pch_ctl2 >> 16; + cpu_ctl2 = I915_READ(BLC_PWM_CPU_CTL2); + if (!panel->backlight.max) panel->backlight.max = get_backlight_max_vbt(connector); @@ -1507,12 +1509,42 @@ static int lpt_setup_backlight(struct intel_connector *connector, enum pipe unus panel->backlight.min = get_backlight_min_vbt(connector); - val = lpt_get_backlight(connector); + panel->backlight.enabled = pch_ctl1 & BLM_PCH_PWM_ENABLE; + + cpu_mode = panel->backlight.enabled && HAS_PCH_LPT(dev_priv) && + !(pch_ctl1 & BLM_PCH_OVERRIDE_ENABLE) && + (cpu_ctl2 & BLM_PWM_ENABLE); + if (cpu_mode) { + u32 freq; + + /* + * We're in cpu mode, convert to PCH units. + * + * Convert CPU pwm tick back to hz, back to new PCH units again. + * this is the same formula as pch_hz_to_pwm, but the other way + * around.. + */ + val = pch_get_backlight(connector); + freq = DIV_ROUND_CLOSEST(KHz(dev_priv->rawclk_freq), val * 128); + + DRM_DEBUG_KMS("Backlight PCH value: %u, converted to freq %u, converted to lpt units %u, minmax: %u/%u\n", + val, freq, lpt_hz_to_pwm(connector, freq), panel->backlight.min, panel->backlight.max); + + val = lpt_hz_to_pwm(connector, freq); + } else + val = lpt_get_backlight(connector); val = intel_panel_compute_brightness(connector, val); panel->backlight.level = clamp(val, panel->backlight.min, panel->backlight.max); - panel->backlight.enabled = pch_ctl1 & BLM_PCH_PWM_ENABLE; + if (cpu_mode) { + /* Write converted CPU PWM value to PCH override register */ + lpt_set_backlight(connector->base.state, panel->backlight.level); + I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1 | BLM_PCH_OVERRIDE_ENABLE); + } + + if (cpu_ctl2 & BLM_PWM_ENABLE) + I915_WRITE(BLC_PWM_CPU_CTL2, cpu_ctl2 & ~BLM_PWM_ENABLE); return 0; } -- 2.19.2 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
