On Tue, 29 Sep 2020, José Roberto de Souza <jose.souza@xxxxxxxxx> wrote:
> Child min_brightness is obsolete from VBT 234+, instead the new
> min_brightness field in the main structure should be used.
>
> This new field is 16 bits wide, so backlight_precision_bits is needed
> to check if value needs to be scaled down but it is only available in
> VBT 236+ so working around it by using the also new backlight_level
> in the main struct.
>
> v2:
> - missed that backlight_data->level is also obsolete
>
> BSpec: 20149
> Signed-off-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_bios.c | 30 +++++++++++++++++--
> drivers/gpu/drm/i915/display/intel_vbt_defs.h | 12 ++++++--
> 2 files changed, 38 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index 4716484af62d..58e5657a77bb 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -425,6 +425,7 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv,
> const struct bdb_lfp_backlight_data *backlight_data;
> const struct lfp_backlight_data_entry *entry;
> int panel_type = dev_priv->vbt.panel_type;
> + u16 level;
>
> backlight_data = find_section(bdb, BDB_LVDS_BACKLIGHT);
> if (!backlight_data)
> @@ -459,14 +460,39 @@ parse_lfp_backlight(struct drm_i915_private *dev_priv,
>
> dev_priv->vbt.backlight.pwm_freq_hz = entry->pwm_freq_hz;
> dev_priv->vbt.backlight.active_low_pwm = entry->active_low_pwm;
> - dev_priv->vbt.backlight.min_brightness = entry->min_brightness;
> +
> + if (bdb->version >= 234) {
> + bool scale = false;
> + u16 min_level;
> +
> + level = backlight_data->backlight_level[panel_type].level;
> + min_level = backlight_data->backlight_min_level[panel_type].level;
> +
> + if (bdb->version >= 236)
> + scale = backlight_data->backlight_precision_bits[panel_type] == 16;
> + else
> + scale = level > 255;
> +
> + if (scale)
> + min_level = min_level / 255;
> +
> + if (min_level > 255) {
> + drm_warn(&dev_priv->drm, "Backlight min level > 255\n");
> + level = 255;
> + }
> + dev_priv->vbt.backlight.min_brightness = min_level;
> + } else {
> + level = backlight_data->level[panel_type];
> + dev_priv->vbt.backlight.min_brightness = entry->min_brightness;
> + }
> +
> drm_dbg_kms(&dev_priv->drm,
> "VBT backlight PWM modulation frequency %u Hz, "
> "active %s, min brightness %u, level %u, controller %u\n",
> dev_priv->vbt.backlight.pwm_freq_hz,
> dev_priv->vbt.backlight.active_low_pwm ? "low" : "high",
> dev_priv->vbt.backlight.min_brightness,
> - backlight_data->level[panel_type],
> + level,
> dev_priv->vbt.backlight.controller);
> }
>
> diff --git a/drivers/gpu/drm/i915/display/intel_vbt_defs.h b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> index 54bcc6a6947c..b4742c4fde97 100644
> --- a/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> +++ b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> @@ -782,7 +782,7 @@ struct lfp_backlight_data_entry {
> u8 active_low_pwm:1;
> u8 obsolete1:5;
> u16 pwm_freq_hz;
> - u8 min_brightness;
> + u8 min_brightness; /* Obsolete from 234+ */
> u8 obsolete2;
> u8 obsolete3;
> } __packed;
> @@ -792,11 +792,19 @@ struct lfp_backlight_control_method {
> u8 controller:4;
> } __packed;
>
> +struct lfp_backlight_level {
> + u32 level : 16;
> + u32 reserved : 16;
That looks like two u16's to me. ;)
BR,
Jani.
> +} __packed;
> +
> struct bdb_lfp_backlight_data {
> u8 entry_size;
> struct lfp_backlight_data_entry data[16];
> - u8 level[16];
> + u8 level[16]; /* Obsolete from 234+ */
> struct lfp_backlight_control_method backlight_control[16];
> + struct lfp_backlight_level backlight_level[16]; /* 234+ */
> + struct lfp_backlight_level backlight_min_level[16]; /* 234+ */
> + u8 backlight_precision_bits[16]; /* 236+ */
> } __packed;
>
> /*
--
Jani Nikula, Intel Open Source Graphics Center
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