On Tue, Nov 20, 2018 at 11:39:26AM +0100, Maarten Lankhorst wrote: > 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. > > 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> > Tested-by: Tolga Cakir <cevelnet@xxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_panel.c | 34 +++++++++++++++++++++++++++--- > 1 file changed, 31 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c > index e6cd7b55c018..3357232f1b0e 100644 > --- a/drivers/gpu/drm/i915/intel_panel.c > +++ b/drivers/gpu/drm/i915/intel_panel.c > @@ -1485,7 +1485,7 @@ 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; > + bool alt, cpu_mode = false; > > if (HAS_PCH_LPT(dev_priv)) > alt = I915_READ(SOUTH_CHICKEN2) & LPT_PWM_GRANULARITY; > @@ -1507,12 +1507,40 @@ 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; > + if (panel->backlight.enabled && HAS_PCH_LPT(dev_priv) && > + (I915_READ(BLC_PWM_CPU_CTL2) & BLM_PWM_ENABLE) && > + !WARN_ON(pch_ctl1 & BLM_PCH_OVERRIDE_ENABLE)) { > + u32 freq; > + > + cpu_mode = true; > + /* > + * 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); The docs are telling me that HSW/BDW use cdclk for the CPU backlight, and the increment is configurable as well. Also what about S4 resume? Don't we need this trick there as well? > + > + 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) { > + u32 tmp; > + > + /* Use PWM mode, instead of cpu clock */ > + lpt_set_backlight(connector->base.state, panel->backlight.level); > + I915_WRITE(BLC_PWM_PCH_CTL1, pch_ctl1 | BLM_PCH_OVERRIDE_ENABLE); > + > + tmp = I915_READ(BLC_PWM_CPU_CTL2); > + I915_WRITE(BLC_PWM_CPU_CTL2, tmp & ~BLM_PWM_ENABLE); > + } > > return 0; > } > -- > 2.19.1 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Ville Syrjälä Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
