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Date: Wed, 9 Dec 2020 20:21:41 -0500
From: Lyude Paul <lyude@...hat.com>
To: dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
intel-gfx@...ts.freedesktop.org
Cc: Jani Nikula <jani.nikula@...el.com>,
Dave Airlie <airlied@...il.com>, greg.depoire@...il.com,
Jani Nikula <jani.nikula@...ux.intel.com>,
Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Ville Syrjälä
<ville.syrjala@...ux.intel.com>, Imre Deak <imre.deak@...el.com>,
José Roberto de Souza <jose.souza@...el.com>,
Manasi Navare <manasi.d.navare@...el.com>,
Sean Paul <seanpaul@...omium.org>,
Lucas De Marchi <lucas.demarchi@...el.com>,
Juha-Pekka Heikkila <juhapekka.heikkila@...il.com>,
Dave Airlie <airlied@...hat.com>,
linux-kernel@...r.kernel.org (open list)
Subject: [RFC 3/5] drm/i915/dp: Remove redundant AUX backlight frequency calculations
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.
Signed-off-by: Lyude Paul <lyude@...hat.com>
Cc: Jani Nikula <jani.nikula@...el.com>
Cc: Dave Airlie <airlied@...il.com>
Cc: greg.depoire@...il.com
---
.../drm/i915/display/intel_display_types.h | 1 +
.../drm/i915/display/intel_dp_aux_backlight.c | 64 ++++++-------------
2 files changed, 19 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 5bc5bfbc4551..133c9cb742a7 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -259,6 +259,7 @@ struct intel_panel {
/* DPCD backlight */
u8 pwmgen_bit_count;
+ u8 pwm_freq_pre_divider;
struct backlight_device *device;
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 4fd536801b14..94ce5ca1affa 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -129,50 +129,6 @@ intel_dp_aux_set_backlight(const struct drm_connector_state *conn_state, u32 lev
}
}
-/*
- * 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_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.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_enable_backlight(const struct intel_crtc_state *crtc_state,
const struct drm_connector_state *conn_state)
{
@@ -213,9 +169,13 @@ static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_st
break;
}
- if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP)
- if (intel_dp_aux_set_pwm_freq(connector))
+ if (panel->backlight.pwm_freq_pre_divider) {
+ if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_FREQ_SET,
+ panel->backlight.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,
@@ -236,6 +196,14 @@ static void intel_dp_aux_disable_backlight(const struct drm_connector_state *old
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_calc_max_backlight(struct intel_connector *connector)
{
struct drm_i915_private *i915 = to_i915(connector->base.dev);
@@ -287,8 +255,10 @@ static u32 intel_dp_aux_calc_max_backlight(struct intel_connector *connector)
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");
@@ -309,7 +279,9 @@ static u32 intel_dp_aux_calc_max_backlight(struct intel_connector *connector)
"Failed to write aux pwmgen bit count\n");
return max_backlight;
}
+
panel->backlight.pwmgen_bit_count = pn;
+ panel->backlight.pwm_freq_pre_divider = f;
max_backlight = (1 << pn) - 1;
--
2.28.0
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