From: Ben Widawsky <benjamin.widawsky@xxxxxxxxx> The fallback values for VLV reflect the Rambi3 panel values. This patch introduces min_brightness member, which defined a part of VBT that has some confusion. The field itself is a byte ranging from 0-255. How this value is supposed to be used by the driver is unclear. Though no code uses it yet, I've written a comment explaining that I intend to use the number in there as an absolute value that represents the minimum duty cycle ratio of the panel. Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx> Signed-off-by: Wayne Boyer <wayne.boyer@xxxxxxxxx> BUG=chrome-os-partner:25159 TEST=suspend/resume test on instrumented system shows correct signaling on oscope. Manual brightness checks. Change-Id: I9f0d8d4fe2778c4768b06459b0a83293b1c6f023 Reviewed-on: https://chromium-review.googlesource.com/196607 Reviewed-by: Aaron Durbin <adurbin@xxxxxxxxxxxx> Tested-by: Wayne Boyer <wayne.boyer@xxxxxxxxx> Commit-Queue: Wayne Boyer <wayne.boyer@xxxxxxxxx> --- drivers/gpu/drm/i915/i915_drv.h | 10 ++++++++++ drivers/gpu/drm/i915/intel_bios.c | 35 ++++++++++++++++++++++++++++++++++- 2 files changed, 44 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 90216bb..1962024 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1261,6 +1261,16 @@ struct intel_vbt_data { u16 pwm_freq_hz; bool present; bool active_low_pwm; + + /* NB: We expect this to be an absolute value (percentage) + * indicating the minimum duty cycle. This value is provided by + * the panel spec, and should be provided in some way/shape/form + * from VBIOS. It's unclear as of this point whether or not + * this is the proper way. + * + * Example, 5 = 5% = .05 + */ + u8 min_duty_cycle_percentage; } backlight; /* MIPI DSI */ diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c index 827498e..557338a 100644 --- a/drivers/gpu/drm/i915/intel_bios.c +++ b/drivers/gpu/drm/i915/intel_bios.c @@ -309,6 +309,20 @@ parse_lfp_panel_data(struct drm_i915_private *dev_priv, } } +#define VLV_DEFAULT_MIN_DUTY_CYCLE_RATIO 5 +static void fake_vlv_backlight(struct drm_i915_private *dev_priv) +{ + dev_priv->vbt.backlight.pwm_freq_hz = 200; + dev_priv->vbt.backlight.active_low_pwm = 0; + dev_priv->vbt.backlight.min_duty_cycle_percentage = VLV_DEFAULT_MIN_DUTY_CYCLE_RATIO; + + DRM_DEBUG_KMS("VBT backlight PWM modulation frequency %u Hz, " + "active %s, min brightness %u\n", + dev_priv->vbt.backlight.pwm_freq_hz, + dev_priv->vbt.backlight.active_low_pwm ? "low" : "high", + dev_priv->vbt.backlight.min_duty_cycle_percentage); +} + static void parse_lfp_backlight(struct drm_i915_private *dev_priv, struct bdb_header *bdb) { @@ -316,8 +330,10 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv, struct bdb_header *bdb) const struct bdb_lfp_backlight_data_entry *entry; backlight_data = find_section(bdb, BDB_LVDS_BACKLIGHT); - if (!backlight_data) + if (!backlight_data && IS_VALLEYVIEW(dev_priv->dev)) { + fake_vlv_backlight(dev_priv); return; + } if (backlight_data->entry_size != sizeof(backlight_data->data[0])) { DRM_DEBUG_KMS("Unsupported backlight data entry size %u\n", @@ -336,6 +352,23 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv, struct bdb_header *bdb) dev_priv->vbt.backlight.pwm_freq_hz = entry->pwm_freq_hz; dev_priv->vbt.backlight.active_low_pwm = entry->active_low_pwm; + + /* NB: It's probably safe to do this for !VLV platforms too. */ + if (IS_VALLEYVIEW(dev_priv->dev) && !entry->min_brightness) + dev_priv->vbt.backlight.min_duty_cycle_percentage = VLV_DEFAULT_MIN_DUTY_CYCLE_RATIO; + else if (entry->min_brightness) { + /* Scale min_duty_cycle_percentage down to an absolute value */ + u32 scaled_bright = entry->min_brightness; + u32 abs_bright = scaled_bright * 100 / 255; + DRM_DEBUG_KMS("Scaling VBT brightness from %d down to absolute %d\n", + scaled_bright, abs_bright); + dev_priv->vbt.backlight.min_duty_cycle_percentage = abs_bright; + } + + /* All platforms should have a PWM */ + if (WARN_ON(!dev_priv->vbt.backlight.pwm_freq_hz)) + dev_priv->vbt.backlight.pwm_freq_hz = 200; + DRM_DEBUG_KMS("VBT backlight PWM modulation frequency %u Hz, " "active %s, min brightness %u, level %u\n", dev_priv->vbt.backlight.pwm_freq_hz, -- 1.7.9.5 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
