From 867cf9cd73c3d31666e4b480aa4f52828d25ac94 Mon Sep 17 00:00:00 2001 From: Lyude Paul Date: Fri, 14 May 2021 14:15:02 -0400 Subject: drm/dp: Extract i915's eDP backlight code into DRM helpers Since we're about to implement eDP backlight support in nouveau using the standard protocol from VESA, we might as well just take the code that's already written for this and move it into a set of shared DRM helpers. Note that these helpers are intended to handle DPCD related backlight control bits such as setting the brightness level over AUX, probing the backlight's TCON, enabling/disabling the backlight over AUX if supported, etc. Any PWM-related portions of backlight control are explicitly left up to the driver, as these will vary from platform to platform. The only exception to this is the calculation of the PWM frequency pre-divider value. This is because the only platform-specific information required for this is the PWM frequency of the panel, which the driver is expected to provide if available. The actual algorithm for calculating this value is standard and is defined in the eDP specification from VESA. Note that these helpers do not yet implement the full range of features the VESA backlight interface provides, and only provide the following functionality (all of which was already present in i915's DPCD backlight support): * Basic control of brightness levels * Basic probing of backlight capabilities * Helpers for enabling and disabling the backlight v3: * Split out changes to i915's backlight code to separate patches to make it easier to review v4: * Style/spelling changes from Thomas Zimmermann v5: * Start using new drm_dbg_*() functions Signed-off-by: Lyude Paul Cc: Jani Nikula Cc: Dave Airlie Cc: greg.depoire@gmail.com Reviewed-by: Rodrigo Vivi Link: https://patchwork.freedesktop.org/patch/msgid/20210514181504.565252-9-lyude@redhat.com --- include/drm/drm_dp_helper.h | 48 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) (limited to 'include') diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 06681bf46d81..0bd6396648b4 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -1801,6 +1801,24 @@ drm_dp_sink_can_do_video_without_timing_msa(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) DP_MSA_TIMING_PAR_IGNORED; } +/** + * drm_edp_backlight_supported() - Check an eDP DPCD for VESA backlight support + * @edp_dpcd: The DPCD to check + * + * Note that currently this function will return %false for panels which support various DPCD + * backlight features but which require the brightness be set through PWM, and don't support setting + * the brightness level via the DPCD. This is a TODO. + * + * Returns: %True if @edp_dpcd indicates that VESA backlight controls are supported, %false + * otherwise + */ +static inline bool +drm_edp_backlight_supported(const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE]) +{ + return (edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP) && + (edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP); +} + /* * DisplayPort AUX channel */ @@ -2107,6 +2125,36 @@ drm_dp_has_quirk(const struct drm_dp_desc *desc, enum drm_dp_quirk quirk) return desc->quirks & BIT(quirk); } +/** + * struct drm_edp_backlight_info - Probed eDP backlight info struct + * @pwmgen_bit_count: The pwmgen bit count + * @pwm_freq_pre_divider: The PWM frequency pre-divider value being used for this backlight, if any + * @max: The maximum backlight level that may be set + * @lsb_reg_used: Do we also write values to the DP_EDP_BACKLIGHT_BRIGHTNESS_LSB register? + * @aux_enable: Does the panel support the AUX enable cap? + * + * This structure contains various data about an eDP backlight, which can be populated by using + * drm_edp_backlight_init(). + */ +struct drm_edp_backlight_info { + u8 pwmgen_bit_count; + u8 pwm_freq_pre_divider; + u16 max; + + bool lsb_reg_used : 1; + bool aux_enable : 1; +}; + +int +drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info *bl, + u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE], + u16 *current_level, u8 *current_mode); +int drm_edp_backlight_set_level(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl, + u16 level); +int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl, + u16 level); +int drm_edp_backlight_disable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl); + #ifdef CONFIG_DRM_DP_CEC void drm_dp_cec_irq(struct drm_dp_aux *aux); void drm_dp_cec_register_connector(struct drm_dp_aux *aux, -- cgit v1.2.3