From 5b1ec9ac7ab5b4520d4db98b7024a8dd5051b000 Mon Sep 17 00:00:00 2001 From: Maarten Lankhorst Date: Tue, 8 Jan 2019 17:08:39 +0100 Subject: [PATCH] drm/i915/backlight: Fix backlight takeover on LPT, v3. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. Changes since v2: - Simplify cpu_mode handling (Jani) Signed-off-by: Maarten Lankhorst Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108225 Cc: Basil Eric Rabi Cc: Hans de Goede Cc: Tolga Cakir Cc: Ville Syrjälä Tested-by: Tolga Cakir Cc: Jani Nikula Reviewed-by: Hans de Goede Reviewed-by: Jani Nikula Link: https://patchwork.freedesktop.org/patch/msgid/20190108160842.13396-2-maarten.lankhorst@linux.intel.com --- drivers/gpu/drm/i915/intel_panel.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c index bb8612ab8ee1..beca98d2b035 100644 --- a/drivers/gpu/drm/i915/intel_panel.c +++ b/drivers/gpu/drm/i915/intel_panel.c @@ -1496,8 +1496,8 @@ 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; @@ -1511,6 +1511,8 @@ 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); @@ -1519,12 +1521,28 @@ 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) + val = pch_get_backlight(connector); + 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) { + DRM_DEBUG_KMS("CPU backlight register was enabled, switching to PCH override\n"); + + /* 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); + + I915_WRITE(BLC_PWM_CPU_CTL2, cpu_ctl2 & ~BLM_PWM_ENABLE); + } return 0; }