On Tue, 08 Jan 2019, Maarten Lankhorst <maarten.lankho...@linux.intel.com>
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.
>
> 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 <maarten.lankho...@linux.intel.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108225
> Cc: Basil Eric Rabi <ericbasil.r...@gmail.com>
> Cc: Hans de Goede <jwrdego...@fedoraproject.org>
> Cc: Tolga Cakir <cevel...@gmail.com>
> Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
> Tested-by: Tolga Cakir <cevel...@gmail.com>
> Cc: Jani Nikula <jani.nik...@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nik...@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 f71b33cf1c97..1c9ef54d58fe 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -1493,8 +1493,8 @@ 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;
> @@ -1508,6 +1508,8 @@ 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);
>
> @@ -1516,12 +1518,28 @@ 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;
> }
--
Jani Nikula, Intel Open Source Graphics Center
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
