drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c

   1 /*
   2  * Copyright © 2015 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  */
  24
  25 #include "intel_display_types.h"
  26 #include "intel_dp_aux_backlight.h"
  27
  28 static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable)
  29 {
  30         struct drm_i915_private *i915 = dp_to_i915(intel_dp);
  31         u8 reg_val = 0;
  32
  33         /* Early return when display use other mechanism to enable backlight. */
  34         if (!(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP))
  35                 return;
  36
  37         if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
  38                               &reg_val) < 0) {
  39                 drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
  40                             DP_EDP_DISPLAY_CONTROL_REGISTER);
  41                 return;
  42         }
  43         if (enable)
  44                 reg_val |= DP_EDP_BACKLIGHT_ENABLE;
  45         else
  46                 reg_val &= ~(DP_EDP_BACKLIGHT_ENABLE);
  47
  48         if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
  49                                reg_val) != 1) {
  50                 drm_dbg_kms(&i915->drm, "Failed to %s aux backlight\n",
  51                             enable ? "enable" : "disable");
  52         }
  53 }
  54
  55 /*
  56  * Read the current backlight value from DPCD register(s) based
  57  * on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
  58  */
  59 static u32 intel_dp_aux_get_backlight(struct intel_connector *connector)
  60 {
  61         struct intel_dp *intel_dp = intel_attached_dp(connector);
  62         struct drm_i915_private *i915 = dp_to_i915(intel_dp);
  63         u8 read_val[2] = { 0x0 };
  64         u8 mode_reg;
  65         u16 level = 0;
  66
  67         if (drm_dp_dpcd_readb(&intel_dp->aux,
  68                               DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
  69                               &mode_reg) != 1) {
  70                 drm_dbg_kms(&i915->drm,
  71                             "Failed to read the DPCD register 0x%x\n",
  72                             DP_EDP_BACKLIGHT_MODE_SET_REGISTER);
  73                 return 0;
  74         }
  75
  76         /*
  77          * If we're not in DPCD control mode yet, the programmed brightness
  78          * value is meaningless and we should assume max brightness
  79          */
  80         if ((mode_reg & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) !=
  81             DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD)
  82                 return connector->panel.backlight.max;
  83
  84         if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
  85                              &read_val, sizeof(read_val)) < 0) {
  86                 drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
  87                             DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
  88                 return 0;
  89         }
  90         level = read_val[0];
  91         if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
  92                 level = (read_val[0] << 8 | read_val[1]);
  93
  94         return level;
  95 }
  96
  97 /*
  98  * Sends the current backlight level over the aux channel, checking if its using
  99  * 8-bit or 16 bit value (MSB and LSB)
 100  */
 101 static void
 102 intel_dp_aux_set_backlight(const struct drm_connector_state *conn_state, u32 level)
 103 {
 104         struct intel_connector *connector = to_intel_connector(conn_state->connector);
 105         struct intel_dp *intel_dp = intel_attached_dp(connector);
 106         struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 107         u8 vals[2] = { 0x0 };
 108
 109         vals[0] = level;
 110
 111         /* Write the MSB and/or LSB */
 112         if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT) {
 113                 vals[0] = (level & 0xFF00) >> 8;
 114                 vals[1] = (level & 0xFF);
 115         }
 116         if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
 117                               vals, sizeof(vals)) < 0) {
 118                 drm_dbg_kms(&i915->drm,
 119                             "Failed to write aux backlight level\n");
 120                 return;
 121         }
 122 }
 123
 124 /*
 125  * Set PWM Frequency divider to match desired frequency in vbt.
 126  * The PWM Frequency is calculated as 27Mhz / (F x P).
 127  * - Where F = PWM Frequency Pre-Divider value programmed by field 7:0 of the
 128  *             EDP_BACKLIGHT_FREQ_SET register (DPCD Address 00728h)
 129  * - Where P = 2^Pn, where Pn is the value programmed by field 4:0 of the
 130  *             EDP_PWMGEN_BIT_COUNT register (DPCD Address 00724h)
 131  */
 132 static bool intel_dp_aux_set_pwm_freq(struct intel_connector *connector)
 133 {
 134         struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
 135         struct intel_dp *intel_dp = intel_attached_dp(connector);
 136         const u8 pn = connector->panel.backlight.pwmgen_bit_count;
 137         int freq, fxp, f, fxp_actual, fxp_min, fxp_max;
 138
 139         freq = dev_priv->vbt.backlight.pwm_freq_hz;
 140         if (!freq) {
 141                 drm_dbg_kms(&dev_priv->drm,
 142                             "Use panel default backlight frequency\n");
 143                 return false;
 144         }
 145
 146         fxp = DIV_ROUND_CLOSEST(KHz(DP_EDP_BACKLIGHT_FREQ_BASE_KHZ), freq);
 147         f = clamp(DIV_ROUND_CLOSEST(fxp, 1 << pn), 1, 255);
 148         fxp_actual = f << pn;
 149
 150         /* Ensure frequency is within 25% of desired value */
 151         fxp_min = DIV_ROUND_CLOSEST(fxp * 3, 4);
 152         fxp_max = DIV_ROUND_CLOSEST(fxp * 5, 4);
 153
 154         if (fxp_min > fxp_actual || fxp_actual > fxp_max) {
 155                 drm_dbg_kms(&dev_priv->drm, "Actual frequency out of range\n");
 156                 return false;
 157         }
 158
 159         if (drm_dp_dpcd_writeb(&intel_dp->aux,
 160                                DP_EDP_BACKLIGHT_FREQ_SET, (u8) f) < 0) {
 161                 drm_dbg_kms(&dev_priv->drm,
 162                             "Failed to write aux backlight freq\n");
 163                 return false;
 164         }
 165         return true;
 166 }
 167
 168 static void intel_dp_aux_enable_backlight(const struct intel_crtc_state *crtc_state,
 169                                           const struct drm_connector_state *conn_state)
 170 {
 171         struct intel_connector *connector = to_intel_connector(conn_state->connector);
 172         struct intel_dp *intel_dp = intel_attached_dp(connector);
 173         struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 174         struct intel_panel *panel = &connector->panel;
 175         u8 dpcd_buf, new_dpcd_buf, edp_backlight_mode;
 176
 177         if (drm_dp_dpcd_readb(&intel_dp->aux,
 178                         DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) != 1) {
 179                 drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
 180                             DP_EDP_BACKLIGHT_MODE_SET_REGISTER);
 181                 return;
 182         }
 183
 184         new_dpcd_buf = dpcd_buf;
 185         edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
 186
 187         switch (edp_backlight_mode) {
 188         case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
 189         case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
 190         case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
 191                 new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
 192                 new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
 193
 194                 if (drm_dp_dpcd_writeb(&intel_dp->aux,
 195                                        DP_EDP_PWMGEN_BIT_COUNT,
 196                                        panel->backlight.pwmgen_bit_count) < 0)
 197                         drm_dbg_kms(&i915->drm,
 198                                     "Failed to write aux pwmgen bit count\n");
 199
 200                 break;
 201
 202         /* Do nothing when it is already DPCD mode */
 203         case DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD:
 204         default:
 205                 break;
 206         }
 207
 208         if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP)
 209                 if (intel_dp_aux_set_pwm_freq(connector))
 210                         new_dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE;
 211
 212         if (new_dpcd_buf != dpcd_buf) {
 213                 if (drm_dp_dpcd_writeb(&intel_dp->aux,
 214                         DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf) < 0) {
 215                         drm_dbg_kms(&i915->drm,
 216                                     "Failed to write aux backlight mode\n");
 217                 }
 218         }
 219
 220         intel_dp_aux_set_backlight(conn_state,
 221                                    connector->panel.backlight.level);
 222         set_aux_backlight_enable(intel_dp, true);
 223 }
 224
 225 static void intel_dp_aux_disable_backlight(const struct drm_connector_state *old_conn_state)
 226 {
 227         set_aux_backlight_enable(enc_to_intel_dp(to_intel_encoder(old_conn_state->best_encoder)),
 228                                  false);
 229 }
 230
 231 static u32 intel_dp_aux_calc_max_backlight(struct intel_connector *connector)
 232 {
 233         struct drm_i915_private *i915 = to_i915(connector->base.dev);
 234         struct intel_dp *intel_dp = intel_attached_dp(connector);
 235         struct intel_panel *panel = &connector->panel;
 236         u32 max_backlight = 0;
 237         int freq, fxp, fxp_min, fxp_max, fxp_actual, f = 1;
 238         u8 pn, pn_min, pn_max;
 239
 240         if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT, &pn) == 1) {
 241                 pn &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
 242                 max_backlight = (1 << pn) - 1;
 243         }
 244
 245         /* Find desired value of (F x P)
 246          * Note that, if F x P is out of supported range, the maximum value or
 247          * minimum value will applied automatically. So no need to check that.
 248          */
 249         freq = i915->vbt.backlight.pwm_freq_hz;
 250         drm_dbg_kms(&i915->drm, "VBT defined backlight frequency %u Hz\n",
 251                     freq);
 252         if (!freq) {
 253                 drm_dbg_kms(&i915->drm,
 254                             "Use panel default backlight frequency\n");
 255                 return max_backlight;
 256         }
 257
 258         fxp = DIV_ROUND_CLOSEST(KHz(DP_EDP_BACKLIGHT_FREQ_BASE_KHZ), freq);
 259
 260         /* Use highest possible value of Pn for more granularity of brightness
 261          * adjustment while satifying the conditions below.
 262          * - Pn is in the range of Pn_min and Pn_max
 263          * - F is in the range of 1 and 255
 264          * - FxP is within 25% of desired value.
 265          *   Note: 25% is arbitrary value and may need some tweak.
 266          */
 267         if (drm_dp_dpcd_readb(&intel_dp->aux,
 268                               DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN, &pn_min) != 1) {
 269                 drm_dbg_kms(&i915->drm,
 270                             "Failed to read pwmgen bit count cap min\n");
 271                 return max_backlight;
 272         }
 273         if (drm_dp_dpcd_readb(&intel_dp->aux,
 274                               DP_EDP_PWMGEN_BIT_COUNT_CAP_MAX, &pn_max) != 1) {
 275                 drm_dbg_kms(&i915->drm,
 276                             "Failed to read pwmgen bit count cap max\n");
 277                 return max_backlight;
 278         }
 279         pn_min &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
 280         pn_max &= DP_EDP_PWMGEN_BIT_COUNT_MASK;
 281
 282         fxp_min = DIV_ROUND_CLOSEST(fxp * 3, 4);
 283         fxp_max = DIV_ROUND_CLOSEST(fxp * 5, 4);
 284         if (fxp_min < (1 << pn_min) || (255 << pn_max) < fxp_max) {
 285                 drm_dbg_kms(&i915->drm,
 286                             "VBT defined backlight frequency out of range\n");
 287                 return max_backlight;
 288         }
 289
 290         for (pn = pn_max; pn >= pn_min; pn--) {
 291                 f = clamp(DIV_ROUND_CLOSEST(fxp, 1 << pn), 1, 255);
 292                 fxp_actual = f << pn;
 293                 if (fxp_min <= fxp_actual && fxp_actual <= fxp_max)
 294                         break;
 295         }
 296
 297         drm_dbg_kms(&i915->drm, "Using eDP pwmgen bit count of %d\n", pn);
 298         if (drm_dp_dpcd_writeb(&intel_dp->aux,
 299                                DP_EDP_PWMGEN_BIT_COUNT, pn) < 0) {
 300                 drm_dbg_kms(&i915->drm,
 301                             "Failed to write aux pwmgen bit count\n");
 302                 return max_backlight;
 303         }
 304         panel->backlight.pwmgen_bit_count = pn;
 305
 306         max_backlight = (1 << pn) - 1;
 307
 308         return max_backlight;
 309 }
 310
 311 static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
 312                                         enum pipe pipe)
 313 {
 314         struct intel_panel *panel = &connector->panel;
 315
 316         panel->backlight.max = intel_dp_aux_calc_max_backlight(connector);
 317         if (!panel->backlight.max)
 318                 return -ENODEV;
 319
 320         panel->backlight.min = 0;
 321         panel->backlight.level = intel_dp_aux_get_backlight(connector);
 322         panel->backlight.enabled = panel->backlight.level != 0;
 323
 324         return 0;
 325 }
 326
 327 static bool
 328 intel_dp_aux_display_control_capable(struct intel_connector *connector)
 329 {
 330         struct intel_dp *intel_dp = intel_attached_dp(connector);
 331         struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 332
 333         /* Check the eDP Display control capabilities registers to determine if
 334          * the panel can support backlight control over the aux channel
 335          */
 336         if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
 337             (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP) &&
 338             !(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP)) {
 339                 drm_dbg_kms(&i915->drm, "AUX Backlight Control Supported!\n");
 340                 return true;
 341         }
 342         return false;
 343 }
 344
 345 int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
 346 {
 347         struct intel_panel *panel = &intel_connector->panel;
 348         struct intel_dp *intel_dp = enc_to_intel_dp(intel_connector->encoder);
 349         struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 350
 351         if (i915->params.enable_dpcd_backlight == 0 ||
 352             !intel_dp_aux_display_control_capable(intel_connector))
 353                 return -ENODEV;
 354
 355         /*
 356          * There are a lot of machines that don't advertise the backlight
 357          * control interface to use properly in their VBIOS, :\
 358          */
 359         if (i915->vbt.backlight.type !=
 360             INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE &&
 361             i915->params.enable_dpcd_backlight != 1 &&
 362             !drm_dp_has_quirk(&intel_dp->desc, intel_dp->edid_quirks,
 363                               DP_QUIRK_FORCE_DPCD_BACKLIGHT)) {
 364                 drm_info(&i915->drm,
 365                          "Panel advertises DPCD backlight support, but "
 366                          "VBT disagrees. If your backlight controls "
 367                          "don't work try booting with "
 368                          "i915.enable_dpcd_backlight=1. If your machine "
 369                          "needs this, please file a _new_ bug report on "
 370                          "drm/i915, see " FDO_BUG_URL " for details.\n");
 371                 return -ENODEV;
 372         }
 373
 374         panel->backlight.setup = intel_dp_aux_setup_backlight;
 375         panel->backlight.enable = intel_dp_aux_enable_backlight;
 376         panel->backlight.disable = intel_dp_aux_disable_backlight;
 377         panel->backlight.set = intel_dp_aux_set_backlight;
 378         panel->backlight.get = intel_dp_aux_get_backlight;
 379
 380         return 0;
 381 }