Noticed this while moving all of the VESA backlight code in i915 over to DRM helpers: it would appear that we calculate the frequency value we want to write to DP_EDP_BACKLIGHT_FREQ_SET twice even though this value never actually changes during runtime. So, let's simplify things by just caching this value in intel_panel.backlight, and re-writing it as-needed.
Changes since v1: * Wrap panel->backlight.edp.vesa.pwm_freq_pre_divider in DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP check - Jani
Signed-off-by: Lyude Paul lyude@redhat.com Cc: Jani Nikula jani.nikula@intel.com Cc: Dave Airlie airlied@gmail.com Cc: greg.depoire@gmail.com --- .../drm/i915/display/intel_display_types.h | 1 + .../drm/i915/display/intel_dp_aux_backlight.c | 65 ++++++------------- 2 files changed, 20 insertions(+), 46 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h index ebaa9d0ed376..1217cde04f0b 100644 --- a/drivers/gpu/drm/i915/display/intel_display_types.h +++ b/drivers/gpu/drm/i915/display/intel_display_types.h @@ -265,6 +265,7 @@ struct intel_panel { union { struct { u8 pwmgen_bit_count; + u8 pwm_freq_pre_divider; } vesa; struct { bool sdr_uses_aux; diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c index 651884390137..62294967f430 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -373,50 +373,6 @@ intel_dp_aux_vesa_set_backlight(const struct drm_connector_state *conn_state, } }
-/* - * Set PWM Frequency divider to match desired frequency in vbt. - * The PWM Frequency is calculated as 27Mhz / (F x P). - * - Where F = PWM Frequency Pre-Divider value programmed by field 7:0 of the - * EDP_BACKLIGHT_FREQ_SET register (DPCD Address 00728h) - * - Where P = 2^Pn, where Pn is the value programmed by field 4:0 of the - * EDP_PWMGEN_BIT_COUNT register (DPCD Address 00724h) - */ -static bool intel_dp_aux_vesa_set_pwm_freq(struct intel_connector *connector) -{ - struct drm_i915_private *dev_priv = to_i915(connector->base.dev); - struct intel_dp *intel_dp = intel_attached_dp(connector); - const u8 pn = connector->panel.backlight.edp.vesa.pwmgen_bit_count; - int freq, fxp, f, fxp_actual, fxp_min, fxp_max; - - freq = dev_priv->vbt.backlight.pwm_freq_hz; - if (!freq) { - drm_dbg_kms(&dev_priv->drm, - "Use panel default backlight frequency\n"); - return false; - } - - fxp = DIV_ROUND_CLOSEST(KHz(DP_EDP_BACKLIGHT_FREQ_BASE_KHZ), freq); - f = clamp(DIV_ROUND_CLOSEST(fxp, 1 << pn), 1, 255); - fxp_actual = f << pn; - - /* Ensure frequency is within 25% of desired value */ - fxp_min = DIV_ROUND_CLOSEST(fxp * 3, 4); - fxp_max = DIV_ROUND_CLOSEST(fxp * 5, 4); - - if (fxp_min > fxp_actual || fxp_actual > fxp_max) { - drm_dbg_kms(&dev_priv->drm, "Actual frequency out of range\n"); - return false; - } - - if (drm_dp_dpcd_writeb(&intel_dp->aux, - DP_EDP_BACKLIGHT_FREQ_SET, (u8) f) < 0) { - drm_dbg_kms(&dev_priv->drm, - "Failed to write aux backlight freq\n"); - return false; - } - return true; -} - static void intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state, const struct drm_connector_state *conn_state, u32 level) @@ -459,9 +415,13 @@ intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state, break; }
- if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP) - if (intel_dp_aux_vesa_set_pwm_freq(connector)) + if (panel->backlight.edp.vesa.pwm_freq_pre_divider) { + if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_FREQ_SET, + panel->backlight.edp.vesa.pwm_freq_pre_divider) == 1) new_dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE; + else + drm_dbg_kms(&i915->drm, "Failed to write aux backlight frequency\n"); + }
if (new_dpcd_buf != dpcd_buf) { if (drm_dp_dpcd_writeb(&intel_dp->aux, @@ -482,6 +442,14 @@ static void intel_dp_aux_vesa_disable_backlight(const struct drm_connector_state false); }
+/* + * Compute PWM frequency divider value based off the frequency provided to us by the vbt. + * The PWM Frequency is calculated as 27Mhz / (F x P). + * - Where F = PWM Frequency Pre-Divider value programmed by field 7:0 of the + * EDP_BACKLIGHT_FREQ_SET register (DPCD Address 00728h) + * - Where P = 2^Pn, where Pn is the value programmed by field 4:0 of the + * EDP_PWMGEN_BIT_COUNT register (DPCD Address 00724h) + */ static u32 intel_dp_aux_vesa_calc_max_backlight(struct intel_connector *connector) { struct drm_i915_private *i915 = to_i915(connector->base.dev); @@ -533,8 +501,10 @@ static u32 intel_dp_aux_vesa_calc_max_backlight(struct intel_connector *connecto pn_min &= DP_EDP_PWMGEN_BIT_COUNT_MASK; pn_max &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
+ /* Ensure frequency is within 25% of desired value */ fxp_min = DIV_ROUND_CLOSEST(fxp * 3, 4); fxp_max = DIV_ROUND_CLOSEST(fxp * 5, 4); + if (fxp_min < (1 << pn_min) || (255 << pn_max) < fxp_max) { drm_dbg_kms(&i915->drm, "VBT defined backlight frequency out of range\n"); @@ -555,7 +525,10 @@ static u32 intel_dp_aux_vesa_calc_max_backlight(struct intel_connector *connecto "Failed to write aux pwmgen bit count\n"); return max_backlight; } + panel->backlight.edp.vesa.pwmgen_bit_count = pn; + if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP) + panel->backlight.edp.vesa.pwm_freq_pre_divider = f;
max_backlight = (1 << pn) - 1;