[RFC 4/5] drm/dp: Extract i915's eDP backlight code into DRM helpers
Jani Nikula
jani.nikula at intel.com
Fri Dec 11 15:01:15 UTC 2020
On Wed, 09 Dec 2020, Lyude Paul <lyude at redhat.com> wrote:
> 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
Overall I like where this is going. Again, not a full review yet, just a
few notes below.
>
> Signed-off-by: Lyude Paul <lyude at redhat.com>
> Cc: Jani Nikula <jani.nikula at intel.com>
> Cc: Dave Airlie <airlied at gmail.com>
> Cc: greg.depoire at gmail.com
> ---
> drivers/gpu/drm/drm_dp_helper.c | 332 ++++++++++++++++++
> .../drm/i915/display/intel_display_types.h | 5 +-
> .../drm/i915/display/intel_dp_aux_backlight.c | 304 ++--------------
> include/drm/drm_dp_helper.h | 48 +++
> 4 files changed, 419 insertions(+), 270 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 5bd0934004e3..06fdddf44e54 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -2596,3 +2596,335 @@ void drm_dp_vsc_sdp_log(const char *level, struct device *dev,
> #undef DP_SDP_LOG
> }
> EXPORT_SYMBOL(drm_dp_vsc_sdp_log);
> +
> +/**
> + * drm_edp_backlight_set_level() - Set the backlight level of an eDP panel via AUX
> + * @aux: The DP AUX channel to use
> + * @bl: Backlight capability info from drm_edp_backlight_init()
> + * @level: The brightness level to set
> + *
> + * Sets the brightness level of an eDP panel's backlight. Note that the panel's backlight must
> + * already have been enabled by the driver by calling drm_edp_backlight_enable().
> + *
> + * Returns: %0 on success, negative error code on failure
> + */
> +int drm_edp_backlight_set_level(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl,
> + u16 level)
I think I'd go for s/backlight/brightness/g function naming thoughout,
to account for OLED. "Backlight" unnecessarily underlines the
technology.
> +{
> + int ret;
> + u8 buf[2] = { 0 };
> +
> + if (bl->lsb_reg_used) {
> + buf[0] = (level & 0xFF00) >> 8;
> + buf[1] = (level & 0x00FF);
> + } else {
> + buf[0] = level;
> + }
> +
> + ret = drm_dp_dpcd_write(aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, buf, sizeof(buf));
> + if (ret != sizeof(buf)) {
> + DRM_ERROR("%s: Failed to write aux backlight level: %d\n", aux->name, ret);
I'd really like to have a way to get from struct drm_dp_aux to struct
drm_device to retain the device specific logging here. It'd be useful in
the lower level dpcd access functions too.
> + return ret < 0 ? ret : -EIO;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_edp_backlight_set_level);
> +
> +static int
> +drm_edp_backlight_set_enable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl,
> + bool enable)
> +{
> + int ret;
> + u8 buf;
> +
> + /* The panel uses something other then DPCD for enabling it's backlight */
> + if (!bl->aux_enable)
> + return 0;
> +
> + ret = drm_dp_dpcd_readb(aux, DP_EDP_DISPLAY_CONTROL_REGISTER, &buf);
> + if (ret != 1) {
> + DRM_ERROR("%s: Failed to read eDP display control register: %d\n", aux->name, ret);
> + return ret < 0 ? ret : -EIO;
> + }
> + if (enable)
> + buf |= DP_EDP_BACKLIGHT_ENABLE;
> + else
> + buf &= ~DP_EDP_BACKLIGHT_ENABLE;
> +
> + ret = drm_dp_dpcd_writeb(aux, DP_EDP_DISPLAY_CONTROL_REGISTER, buf);
> + if (ret != 1) {
> + DRM_ERROR("%s: Failed to write eDP display control register: %d\n", aux->name, ret);
> + return ret < 0 ? ret : -EIO;
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * drm_edp_backlight_enable() - Enable an eDP panel's backlight using DPCD
> + * @aux: The DP AUX channel to use
> + * @bl: Backlight capability info from drm_edp_backlight_init()
> + * @level: The initial backlight level to set via AUX, if there is one
> + *
> + * This function handles enabling DPCD backlight controls on a panel over DPCD, while additionally
> + * restoring any important backlight state such as the given backlight level, the brightness byte
> + * count, backlight frequency, etc.
> + *
> + * Note that certain panels, while supporting brightness level controls over DPCD, may not support
> + * having their backlights enabled via the standard %DP_EDP_DISPLAY_CONTROL_REGISTER. On such panels
> + * &drm_edp_backlight_info.aux_enable will be set to %false, this function will skip the step of
> + * programming the %DP_EDP_DISPLAY_CONTROL_REGISTER, and the driver must perform the required
> + * implementation specific step for enabling the backlight after calling this function.
> + *
> + * Returns: %0 on success, negative error code on failure.
> + */
> +int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl,
> + const u16 level)
> +{
> + int ret;
> + u8 dpcd_buf, new_dpcd_buf;
> +
> + ret = drm_dp_dpcd_readb(aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf);
> + if (ret != 1) {
> + DRM_DEBUG_KMS("%s: Failed to read backlight mode: %d\n", aux->name, ret);
> + return ret < 0 ? ret : -EIO;
> + }
> +
> + new_dpcd_buf = dpcd_buf;
> +
> + if ((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) != DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {
> + new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> + new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> +
> + ret = drm_dp_dpcd_writeb(aux, DP_EDP_PWMGEN_BIT_COUNT, bl->pwmgen_bit_count);
> + if (ret != 1)
> + DRM_DEBUG_KMS("%s: Failed to write aux pwmgen bit count: %d\n",
> + aux->name, ret);
> + }
> +
> + if (bl->pwm_freq_pre_divider) {
> + ret = drm_dp_dpcd_writeb(aux, DP_EDP_BACKLIGHT_FREQ_SET, bl->pwm_freq_pre_divider);
> + if (ret != 1)
> + DRM_DEBUG_KMS("%s: Failed to write aux backlight frequency: %d\n",
> + aux->name, ret);
> + else
> + new_dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE;
> + }
> +
> + if (new_dpcd_buf != dpcd_buf) {
> + ret = drm_dp_dpcd_writeb(aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf);
> + if (ret != 1) {
> + DRM_DEBUG_KMS("%s: Failed to write aux backlight mode: %d\n",
> + aux->name, ret);
> + return ret < 0 ? ret : -EIO;
> + }
> + }
> +
> + ret = drm_edp_backlight_set_level(aux, bl, level);
> + if (ret < 0)
> + return ret;
> + ret = drm_edp_backlight_set_enable(aux, bl, true);
> + if (ret < 0)
> + return ret;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_edp_backlight_enable);
> +
> +/**
> + * drm_edp_backlight_disable() - Disable an eDP backlight using DPCD, if supported
> + * @aux: The DP AUX channel to use
> + * @bl: Backlight capability info from drm_edp_backlight_init()
> + *
> + * This function handles disabling DPCD backlight controls on a panel over AUX. Note that some
> + * panels have backlights that are enabled/disabled by other means, despite having their brightness
> + * values controlled through DPCD. On such panels &drm_edp_backlight_info.aux_enable will be set to
> + * %false, this function will become a no-op (and we will skip updating
> + * %DP_EDP_DISPLAY_CONTROL_REGISTER), and the driver must take care to perform it's own
> + * implementation specific step for disabling the backlight.
> + *
> + * Returns: %0 on success or no-op, negative error code on failure.
> + */
> +int drm_edp_backlight_disable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl)
> +{
> + int ret;
> +
> + ret = drm_edp_backlight_set_enable(aux, bl, false);
> + if (ret < 0)
> + return ret;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_edp_backlight_disable);
> +
> +static inline int
> +drm_edp_backlight_probe_max(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])
> +{
> + int fxp, fxp_min, fxp_max, fxp_actual, f = 1;
> + int ret;
> + u8 pn, pn_min, pn_max;
> +
> + ret = drm_dp_dpcd_readb(aux, DP_EDP_PWMGEN_BIT_COUNT, &pn);
> + if (ret != 1) {
> + DRM_DEBUG_KMS("%s: Failed to read pwmgen bit count cap: %d\n", aux->name, ret);
> + return -ENODEV;
> + }
> +
> + pn &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
> + bl->max = (1 << pn) - 1;
> + if (!driver_pwm_freq_hz)
> + return 0;
> +
> + /*
> + * Set PWM Frequency divider to match desired frequency provided by the driver.
> + * 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)
> + */
> +
> + /* Find desired value of (F x P)
> + * Note that, if F x P is out of supported range, the maximum value or minimum value will
> + * applied automatically. So no need to check that.
> + */
> + fxp = DIV_ROUND_CLOSEST(1000 * DP_EDP_BACKLIGHT_FREQ_BASE_KHZ, driver_pwm_freq_hz);
> +
> + /* Use highest possible value of Pn for more granularity of brightness adjustment while
> + * satifying the conditions below.
> + * - Pn is in the range of Pn_min and Pn_max
> + * - F is in the range of 1 and 255
> + * - FxP is within 25% of desired value.
> + * Note: 25% is arbitrary value and may need some tweak.
> + */
> + ret = drm_dp_dpcd_readb(aux, DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN, &pn_min);
> + if (ret != 1) {
> + DRM_DEBUG_KMS("%s: Failed to read pwmgen bit count cap min: %d\n", aux->name, ret);
> + return 0;
> + }
> + ret = drm_dp_dpcd_readb(aux, DP_EDP_PWMGEN_BIT_COUNT_CAP_MAX, &pn_max);
> + if (ret != 1) {
> + DRM_DEBUG_KMS("%s: Failed to read pwmgen bit count cap max: %d\n", aux->name, ret);
> + return 0;
> + }
> + 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_DEBUG_KMS("%s: Driver defined backlight frequency (%d) out of range\n",
> + aux->name, driver_pwm_freq_hz);
> + return 0;
> + }
> +
> + for (pn = pn_max; pn >= pn_min; pn--) {
> + f = clamp(DIV_ROUND_CLOSEST(fxp, 1 << pn), 1, 255);
> + fxp_actual = f << pn;
> + if (fxp_min <= fxp_actual && fxp_actual <= fxp_max)
> + break;
> + }
> +
> + ret = drm_dp_dpcd_writeb(aux, DP_EDP_PWMGEN_BIT_COUNT, pn);
> + if (ret != 1) {
> + DRM_DEBUG_KMS("%s: Failed to write aux pwmgen bit count: %d\n", aux->name, ret);
> + return 0;
> + }
> + bl->pwmgen_bit_count = pn;
> + bl->max = (1 << pn) - 1;
> +
> + if (edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP) {
> + bl->pwm_freq_pre_divider = f;
> + DRM_DEBUG_KMS("%s: Using backlight frequency from driver (%dHz)\n",
> + aux->name, driver_pwm_freq_hz);
> + }
> +
> + return 0;
> +}
> +
> +static inline int
> +drm_edp_backlight_probe_level(struct drm_dp_aux *aux, struct drm_edp_backlight_info *bl,
> + u8 *current_mode)
> +{
> + int ret;
> + u8 buf[2];
> + u8 mode_reg;
> +
> + ret = drm_dp_dpcd_readb(aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &mode_reg);
> + if (ret != 1) {
> + DRM_DEBUG_KMS("%s: Failed to read backlight mode: %d\n", aux->name, ret);
> + return ret < 0 ? ret : -EIO;
> + }
> +
> + *current_mode = (mode_reg & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK);
> + if (*current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {
> + int size = 1 + bl->lsb_reg_used;
> +
> + ret = drm_dp_dpcd_read(aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, buf, size);
> + if (ret != size) {
> + DRM_DEBUG_KMS("%s: Failed to read backlight level: %d\n", aux->name, ret);
> + return ret < 0 ? ret : -EIO;
> + }
> +
> + if (bl->lsb_reg_used)
> + return (buf[0] << 8) | buf[1];
> + else
> + return buf[0];
> + }
> +
> + /*
> + * If we're not in DPCD control mode yet, the programmed brightness value is meaningless and
> + * the driver should assume max brightness
> + */
> + return bl->max;
> +}
> +
> +/**
> + * drm_edp_backlight_init() - Probe a display panel's TCON using the standard VESA eDP backlight
> + * interface.
> + * @aux: The DP aux device to use for probing
> + * @bl: The &drm_edp_backlight_info struct to fill out with information on the backlight
> + * @driver_pwm_freq_hz: Optional PWM frequency from the driver in hz
> + * @edp_dpcd: A cached copy of the eDP DPCD
> + * @current_level: Where to store the probed brightness level
> + * @current_mode: Where to store the currently set backlight control mode
> + *
> + * Initializes a &drm_edp_backlight_info struct by probing @aux for it's backlight capabilities,
> + * along with also probing the current and maximum supported brightness levels.
> + *
> + * If @driver_pwm_freq_hz is non-zero, this will be used as the backlight frequency. Otherwise, the
> + * default frequency from the panel is used.
> + *
> + * Returns: %0 on success, negative error code on failure.
> + */
> +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 ret;
> +
> + if (edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP)
> + bl->aux_enable = true;
> + if (edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
> + bl->lsb_reg_used = true;
> +
> + ret = drm_edp_backlight_probe_max(aux, bl, driver_pwm_freq_hz, edp_dpcd);
> + if (ret < 0)
> + return ret;
> +
> + ret = drm_edp_backlight_probe_level(aux, bl, current_mode);
> + if (ret < 0)
> + return ret;
> + *current_level = ret;
> +
> + DRM_DEBUG_KMS("%s: Found backlight level=%d/%d pwm_freq_pre_divider=%d mode=%x\n",
> + aux->name, *current_level, bl->max, bl->pwm_freq_pre_divider, *current_mode);
> + DRM_DEBUG_KMS("%s: Backlight caps: pwmgen_bit_count=%d lsb_reg_used=%d aux_enable=%d\n",
> + aux->name, bl->pwmgen_bit_count, bl->lsb_reg_used, bl->aux_enable);
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_edp_backlight_init);
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 133c9cb742a7..82673e8f21c3 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -257,11 +257,8 @@ struct intel_panel {
> struct pwm_device *pwm;
> struct pwm_state pwm_state;
>
> - /* DPCD backlight */
> - u8 pwmgen_bit_count;
> - u8 pwm_freq_pre_divider;
> -
> struct backlight_device *device;
> + struct drm_edp_backlight_info vesa_edp_info;
>
> const struct intel_panel_bl_funcs *funcs;
> void (*power)(struct intel_connector *, bool enable);
> 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 94ce5ca1affa..b1ebfd854a42 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> @@ -25,303 +25,73 @@
> #include "intel_display_types.h"
> #include "intel_dp_aux_backlight.h"
>
> -static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable)
> -{
> - struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> - u8 reg_val = 0;
> -
> - /* Early return when display use other mechanism to enable backlight. */
> - if (!(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP))
> - return;
> -
> - if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
> - ®_val) < 0) {
> - drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
> - DP_EDP_DISPLAY_CONTROL_REGISTER);
> - return;
> - }
> - if (enable)
> - reg_val |= DP_EDP_BACKLIGHT_ENABLE;
> - else
> - reg_val &= ~(DP_EDP_BACKLIGHT_ENABLE);
> -
> - if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
> - reg_val) != 1) {
> - drm_dbg_kms(&i915->drm, "Failed to %s aux backlight\n",
> - enable ? "enable" : "disable");
> - }
> -}
> -
> -static bool intel_dp_aux_backlight_dpcd_mode(struct intel_connector *connector)
> -{
> - struct intel_dp *intel_dp = intel_attached_dp(connector);
> - struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> - u8 mode_reg;
> -
> - if (drm_dp_dpcd_readb(&intel_dp->aux,
> - DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
> - &mode_reg) != 1) {
> - drm_dbg_kms(&i915->drm,
> - "Failed to read the DPCD register 0x%x\n",
> - DP_EDP_BACKLIGHT_MODE_SET_REGISTER);
> - return false;
> - }
> -
> - return (mode_reg & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
> - DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> -}
> -
> -/*
> - * Read the current backlight value from DPCD register(s) based
> - * on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
> - */
> static u32 intel_dp_aux_get_backlight(struct intel_connector *connector)
> {
> - struct intel_dp *intel_dp = intel_attached_dp(connector);
> - struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> - u8 read_val[2] = { 0x0 };
> - u16 level = 0;
> -
> - /*
> - * If we're not in DPCD control mode yet, the programmed brightness
> - * value is meaningless and we should assume max brightness
> - */
> - if (!intel_dp_aux_backlight_dpcd_mode(connector))
> - return connector->panel.backlight.max;
> -
> - if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
> - &read_val, sizeof(read_val)) < 0) {
> - drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
> - DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
> - return 0;
> - }
> - level = read_val[0];
> - if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
> - level = (read_val[0] << 8 | read_val[1]);
> -
> - return level;
> + return connector->panel.backlight.level;
> }
>
> -/*
> - * Sends the current backlight level over the aux channel, checking if its using
> - * 8-bit or 16 bit value (MSB and LSB)
> - */
> static void
> -intel_dp_aux_set_backlight(const struct drm_connector_state *conn_state, u32 level)
> +intel_dp_aux_set_backlight(const struct drm_connector_state *conn_state,
> + u32 level)
> {
> struct intel_connector *connector = to_intel_connector(conn_state->connector);
> - struct intel_dp *intel_dp = intel_attached_dp(connector);
> - struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> - u8 vals[2] = { 0x0 };
> -
> - vals[0] = level;
> + struct intel_panel *panel = &connector->panel;
> + struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
>
> - /* Write the MSB and/or LSB */
> - if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT) {
> - vals[0] = (level & 0xFF00) >> 8;
> - vals[1] = (level & 0xFF);
> - }
> - if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
> - vals, sizeof(vals)) < 0) {
> - drm_dbg_kms(&i915->drm,
> - "Failed to write aux backlight level\n");
> - return;
> - }
> + drm_edp_backlight_set_level(&intel_dp->aux, &panel->backlight.vesa_edp_info, level);
> }
>
> -static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_state,
> - const struct drm_connector_state *conn_state)
> +static void
> +intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_state,
> + const struct drm_connector_state *conn_state)
> {
> struct intel_connector *connector = to_intel_connector(conn_state->connector);
> - struct intel_dp *intel_dp = intel_attached_dp(connector);
> - struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> struct intel_panel *panel = &connector->panel;
> - u8 dpcd_buf, new_dpcd_buf, edp_backlight_mode;
> -
> - if (drm_dp_dpcd_readb(&intel_dp->aux,
> - DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) != 1) {
> - drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
> - DP_EDP_BACKLIGHT_MODE_SET_REGISTER);
> - return;
> - }
> -
> - new_dpcd_buf = dpcd_buf;
> - edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> -
> - switch (edp_backlight_mode) {
> - case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
> - case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
> - case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
> - new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> - new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> -
> - if (drm_dp_dpcd_writeb(&intel_dp->aux,
> - DP_EDP_PWMGEN_BIT_COUNT,
> - panel->backlight.pwmgen_bit_count) < 0)
> - drm_dbg_kms(&i915->drm,
> - "Failed to write aux pwmgen bit count\n");
> -
> - break;
> -
> - /* Do nothing when it is already DPCD mode */
> - case DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD:
> - default:
> - break;
> - }
> -
> - 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");
> - }
> + struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
>
> - if (new_dpcd_buf != dpcd_buf) {
> - if (drm_dp_dpcd_writeb(&intel_dp->aux,
> - DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf) < 0) {
> - drm_dbg_kms(&i915->drm,
> - "Failed to write aux backlight mode\n");
> - }
> - }
> -
> - intel_dp_aux_set_backlight(conn_state,
> - connector->panel.backlight.level);
> - set_aux_backlight_enable(intel_dp, true);
> + drm_edp_backlight_enable(&intel_dp->aux, &panel->backlight.vesa_edp_info,
> + panel->backlight.level);
> }
>
> -static void intel_dp_aux_disable_backlight(const struct drm_connector_state *old_conn_state)
> -{
> - set_aux_backlight_enable(enc_to_intel_dp(to_intel_encoder(old_conn_state->best_encoder)),
> - 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)
> +static void
> +intel_dp_aux_disable_backlight(const struct drm_connector_state *old_conn_state)
> {
> - struct drm_i915_private *i915 = to_i915(connector->base.dev);
> - struct intel_dp *intel_dp = intel_attached_dp(connector);
> + struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
> struct intel_panel *panel = &connector->panel;
> - u32 max_backlight = 0;
> - int freq, fxp, fxp_min, fxp_max, fxp_actual, f = 1;
> - u8 pn, pn_min, pn_max;
> -
> - if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT, &pn) == 1) {
> - pn &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
> - max_backlight = (1 << pn) - 1;
> - }
> -
> - /* Find desired value of (F x P)
> - * Note that, if F x P is out of supported range, the maximum value or
> - * minimum value will applied automatically. So no need to check that.
> - */
> - freq = i915->vbt.backlight.pwm_freq_hz;
> - drm_dbg_kms(&i915->drm, "VBT defined backlight frequency %u Hz\n",
> - freq);
> - if (!freq) {
> - drm_dbg_kms(&i915->drm,
> - "Use panel default backlight frequency\n");
> - return max_backlight;
> - }
> -
> - fxp = DIV_ROUND_CLOSEST(KHz(DP_EDP_BACKLIGHT_FREQ_BASE_KHZ), freq);
> -
> - /* Use highest possible value of Pn for more granularity of brightness
> - * adjustment while satifying the conditions below.
> - * - Pn is in the range of Pn_min and Pn_max
> - * - F is in the range of 1 and 255
> - * - FxP is within 25% of desired value.
> - * Note: 25% is arbitrary value and may need some tweak.
> - */
> - if (drm_dp_dpcd_readb(&intel_dp->aux,
> - DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN, &pn_min) != 1) {
> - drm_dbg_kms(&i915->drm,
> - "Failed to read pwmgen bit count cap min\n");
> - return max_backlight;
> - }
> - if (drm_dp_dpcd_readb(&intel_dp->aux,
> - DP_EDP_PWMGEN_BIT_COUNT_CAP_MAX, &pn_max) != 1) {
> - drm_dbg_kms(&i915->drm,
> - "Failed to read pwmgen bit count cap max\n");
> - return max_backlight;
> - }
> - pn_min &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
> - pn_max &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
> + struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
>
> - /* 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");
> - return max_backlight;
> - }
> -
> - for (pn = pn_max; pn >= pn_min; pn--) {
> - f = clamp(DIV_ROUND_CLOSEST(fxp, 1 << pn), 1, 255);
> - fxp_actual = f << pn;
> - if (fxp_min <= fxp_actual && fxp_actual <= fxp_max)
> - break;
> - }
> -
> - drm_dbg_kms(&i915->drm, "Using eDP pwmgen bit count of %d\n", pn);
> - if (drm_dp_dpcd_writeb(&intel_dp->aux,
> - DP_EDP_PWMGEN_BIT_COUNT, pn) < 0) {
> - drm_dbg_kms(&i915->drm,
> - "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;
> -
> - return max_backlight;
> + drm_edp_backlight_disable(&intel_dp->aux, &panel->backlight.vesa_edp_info);
> }
>
> static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
> enum pipe pipe)
> {
> struct intel_panel *panel = &connector->panel;
> + struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
> + struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> + u16 current_level;
> + u8 current_mode;
> + int ret;
>
> - panel->backlight.max = intel_dp_aux_calc_max_backlight(connector);
> - if (!panel->backlight.max)
> - return -ENODEV;
> + ret = drm_edp_backlight_init(&intel_dp->aux, &panel->backlight.vesa_edp_info,
> + i915->vbt.backlight.pwm_freq_hz, intel_dp->edp_dpcd,
> + ¤t_level, ¤t_mode);
> + if (ret < 0)
> + return ret;
>
> + panel->backlight.max = panel->backlight.vesa_edp_info.max;
> panel->backlight.min = 0;
> - panel->backlight.level = intel_dp_aux_get_backlight(connector);
> - panel->backlight.enabled = intel_dp_aux_backlight_dpcd_mode(connector) &&
> - panel->backlight.level != 0;
> + if (current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {
> + panel->backlight.level = current_level;
> + panel->backlight.enabled = panel->backlight.level != 0;
> + } else {
> + panel->backlight.level = panel->backlight.max;
> + panel->backlight.enabled = false;
> + }
>
> return 0;
> }
>
> -static bool
> -intel_dp_aux_display_control_capable(struct intel_connector *connector)
> -{
> - struct intel_dp *intel_dp = intel_attached_dp(connector);
> - struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> -
> - /* Check the eDP Display control capabilities registers to determine if
> - * the panel can support backlight control over the aux channel
> - */
> - if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
> - (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) {
> - drm_dbg_kms(&i915->drm, "AUX Backlight Control Supported!\n");
> - return true;
> - }
> - return false;
> -}
> -
> static const struct intel_panel_bl_funcs intel_dp_bl_funcs = {
> .setup = intel_dp_aux_setup_backlight,
> .enable = intel_dp_aux_enable_backlight,
> @@ -337,9 +107,11 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
> struct drm_i915_private *i915 = dp_to_i915(intel_dp);
>
> if (i915->params.enable_dpcd_backlight == 0 ||
> - !intel_dp_aux_display_control_capable(intel_connector))
> + !drm_edp_backlight_supported(intel_dp->edp_dpcd))
> return -ENODEV;
>
> + drm_dbg_kms(&i915->drm, "AUX Backlight Control Supported!\n");
> +
> /*
> * There are a lot of machines that don't advertise the backlight
> * control interface to use properly in their VBIOS, :\
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 6b40258927bf..082fb832d4f6 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1598,6 +1598,24 @@ 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
> */
> @@ -1912,6 +1930,36 @@ drm_dp_has_quirk(const struct drm_dp_desc *desc, u32 edid_quirks,
> return (desc->quirks | edid_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,
--
Jani Nikula, Intel Open Source Graphics Center
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