diff options
Diffstat (limited to 'drivers/gpu/drm/drm_dp_helper.c')
| -rw-r--r-- | drivers/gpu/drm/drm_dp_helper.c | 347 |
1 files changed, 347 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 55b53df6ce34..24bbc710c825 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -3115,3 +3115,350 @@ int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8 color_spc) return 0; } EXPORT_SYMBOL(drm_dp_pcon_convert_rgb_to_ycbcr); + +/** + * 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) +{ + 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_err(aux->drm_dev, + "%s: Failed to write aux backlight level: %d\n", + aux->name, ret); + 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 its backlight */ + if (!bl->aux_enable) + return 0; + + ret = drm_dp_dpcd_readb(aux, DP_EDP_DISPLAY_CONTROL_REGISTER, &buf); + if (ret != 1) { + drm_err(aux->drm_dev, "%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_err(aux->drm_dev, "%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_dbg_kms(aux->drm_dev, + "%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_dbg_kms(aux->drm_dev, "%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_dbg_kms(aux->drm_dev, + "%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_dbg_kms(aux->drm_dev, "%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_dbg_kms(aux->drm_dev, "%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_dbg_kms(aux->drm_dev, "%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_dbg_kms(aux->drm_dev, "%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_dbg_kms(aux->drm_dev, + "%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_dbg_kms(aux->drm_dev, "%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_dbg_kms(aux->drm_dev, "%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_dbg_kms(aux->drm_dev, "%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_dbg_kms(aux->drm_dev, "%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_dbg_kms(aux->drm_dev, + "%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_dbg_kms(aux->drm_dev, + "%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); |