intel_bios.c

Go to the documentation of this file.

/*
 * Copyright © 2006 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <[email protected]>
 *
 */
#include <linux/dmi.h>
#include <drm/drm_dp_helper.h>
#include <drm/drmP.h>
#include <drm/i915_drm.h>
#include "i915_drv.h"
#include "intel_bios.h"

#define SLAVE_ADDR1 0x70
#define SLAVE_ADDR2 0x72

static int panel_type;

static void *
find_section(struct bdb_header *bdb, int section_id)
{
    u8 *base = (u8 *)bdb;
    int index = 0;
    u16 total, current_size;
    u8 current_id;

    /* skip to first section */
    index += bdb->header_size;
    total = bdb->bdb_size;

    /* walk the sections looking for section_id */
    while (index < total) {
        current_id = *(base + index);
        index++;
        current_size = *((u16 *)(base + index));
        index += 2;
        if (current_id == section_id)
            return base + index;
        index += current_size;
    }

    return NULL;
}

static u16
get_blocksize(void *p)
{
    u16 *block_ptr, block_size;

    block_ptr = (u16 *)((char *)p - 2);
    block_size = *block_ptr;
    return block_size;
}

static void
fill_detail_timing_data(struct drm_display_mode *panel_fixed_mode,
            const struct lvds_dvo_timing *dvo_timing)
{
    panel_fixed_mode->hdisplay = (dvo_timing->hactive_hi << 8) |
        dvo_timing->hactive_lo;
    panel_fixed_mode->hsync_start = panel_fixed_mode->hdisplay +
        ((dvo_timing->hsync_off_hi << 8) | dvo_timing->hsync_off_lo);
    panel_fixed_mode->hsync_end = panel_fixed_mode->hsync_start +
        dvo_timing->hsync_pulse_width;
    panel_fixed_mode->htotal = panel_fixed_mode->hdisplay +
        ((dvo_timing->hblank_hi << 8) | dvo_timing->hblank_lo);

    panel_fixed_mode->vdisplay = (dvo_timing->vactive_hi << 8) |
        dvo_timing->vactive_lo;
    panel_fixed_mode->vsync_start = panel_fixed_mode->vdisplay +
        dvo_timing->vsync_off;
    panel_fixed_mode->vsync_end = panel_fixed_mode->vsync_start +
        dvo_timing->vsync_pulse_width;
    panel_fixed_mode->vtotal = panel_fixed_mode->vdisplay +
        ((dvo_timing->vblank_hi << 8) | dvo_timing->vblank_lo);
    panel_fixed_mode->clock = dvo_timing->clock * 10;
    panel_fixed_mode->type = DRM_MODE_TYPE_PREFERRED;

    if (dvo_timing->hsync_positive)
        panel_fixed_mode->flags |= DRM_MODE_FLAG_PHSYNC;
    else
        panel_fixed_mode->flags |= DRM_MODE_FLAG_NHSYNC;

    if (dvo_timing->vsync_positive)
        panel_fixed_mode->flags |= DRM_MODE_FLAG_PVSYNC;
    else
        panel_fixed_mode->flags |= DRM_MODE_FLAG_NVSYNC;

    /* Some VBTs have bogus h/vtotal values */
    if (panel_fixed_mode->hsync_end > panel_fixed_mode->htotal)
        panel_fixed_mode->htotal = panel_fixed_mode->hsync_end + 1;
    if (panel_fixed_mode->vsync_end > panel_fixed_mode->vtotal)
        panel_fixed_mode->vtotal = panel_fixed_mode->vsync_end + 1;

    drm_mode_set_name(panel_fixed_mode);
}

static bool
lvds_dvo_timing_equal_size(const struct lvds_dvo_timing *a,
               const struct lvds_dvo_timing *b)
{
    if (a->hactive_hi != b->hactive_hi ||
        a->hactive_lo != b->hactive_lo)
        return false;

    if (a->hsync_off_hi != b->hsync_off_hi ||
        a->hsync_off_lo != b->hsync_off_lo)
        return false;

    if (a->hsync_pulse_width != b->hsync_pulse_width)
        return false;

    if (a->hblank_hi != b->hblank_hi ||
        a->hblank_lo != b->hblank_lo)
        return false;

    if (a->vactive_hi != b->vactive_hi ||
        a->vactive_lo != b->vactive_lo)
        return false;

    if (a->vsync_off != b->vsync_off)
        return false;

    if (a->vsync_pulse_width != b->vsync_pulse_width)
        return false;

    if (a->vblank_hi != b->vblank_hi ||
        a->vblank_lo != b->vblank_lo)
        return false;

    return true;
}

static const struct lvds_dvo_timing *
get_lvds_dvo_timing(const struct bdb_lvds_lfp_data *lvds_lfp_data,
            const struct bdb_lvds_lfp_data_ptrs *lvds_lfp_data_ptrs,
            int index)
{
    /*
     * the size of fp_timing varies on the different platform.
     * So calculate the DVO timing relative offset in LVDS data
     * entry to get the DVO timing entry
     */

    int lfp_data_size =
        lvds_lfp_data_ptrs->ptr[1].dvo_timing_offset -
        lvds_lfp_data_ptrs->ptr[0].dvo_timing_offset;
    int dvo_timing_offset =
        lvds_lfp_data_ptrs->ptr[0].dvo_timing_offset -
        lvds_lfp_data_ptrs->ptr[0].fp_timing_offset;
    char *entry = (char *)lvds_lfp_data->data + lfp_data_size * index;

    return (struct lvds_dvo_timing *)(entry + dvo_timing_offset);
}

/* get lvds_fp_timing entry
 * this function may return NULL if the corresponding entry is invalid
 */
static const struct lvds_fp_timing *
get_lvds_fp_timing(const struct bdb_header *bdb,
           const struct bdb_lvds_lfp_data *data,
           const struct bdb_lvds_lfp_data_ptrs *ptrs,
           int index)
{
    size_t data_ofs = (const u8 *)data - (const u8 *)bdb;
    u16 data_size = ((const u16 *)data)[-1]; /* stored in header */
    size_t ofs;

    if (index >= ARRAY_SIZE(ptrs->ptr))
        return NULL;
    ofs = ptrs->ptr[index].fp_timing_offset;
    if (ofs < data_ofs ||
        ofs + sizeof(struct lvds_fp_timing) > data_ofs + data_size)
        return NULL;
    return (const struct lvds_fp_timing *)((const u8 *)bdb + ofs);
}

/* Try to find integrated panel data */
static void
parse_lfp_panel_data(struct drm_i915_private *dev_priv,
                struct bdb_header *bdb)
{
    const struct bdb_lvds_options *lvds_options;
    const struct bdb_lvds_lfp_data *lvds_lfp_data;
    const struct bdb_lvds_lfp_data_ptrs *lvds_lfp_data_ptrs;
    const struct lvds_dvo_timing *panel_dvo_timing;
    const struct lvds_fp_timing *fp_timing;
    struct drm_display_mode *panel_fixed_mode;
    int i, downclock;

    lvds_options = find_section(bdb, BDB_LVDS_OPTIONS);
    if (!lvds_options)
        return;

    dev_priv->lvds_dither = lvds_options->pixel_dither;
    if (lvds_options->panel_type == 0xff)
        return;

    panel_type = lvds_options->panel_type;

    lvds_lfp_data = find_section(bdb, BDB_LVDS_LFP_DATA);
    if (!lvds_lfp_data)
        return;

    lvds_lfp_data_ptrs = find_section(bdb, BDB_LVDS_LFP_DATA_PTRS);
    if (!lvds_lfp_data_ptrs)
        return;

    dev_priv->lvds_vbt = 1;

    panel_dvo_timing = get_lvds_dvo_timing(lvds_lfp_data,
                           lvds_lfp_data_ptrs,
                           lvds_options->panel_type);

    panel_fixed_mode = kzalloc(sizeof(*panel_fixed_mode), GFP_KERNEL);
    if (!panel_fixed_mode)
        return;

    fill_detail_timing_data(panel_fixed_mode, panel_dvo_timing);

    dev_priv->lfp_lvds_vbt_mode = panel_fixed_mode;

    DRM_DEBUG_KMS("Found panel mode in BIOS VBT tables:\n");
    drm_mode_debug_printmodeline(panel_fixed_mode);

    /*
     * Iterate over the LVDS panel timing info to find the lowest clock
     * for the native resolution.
     */
    downclock = panel_dvo_timing->clock;
    for (i = 0; i < 16; i++) {
        const struct lvds_dvo_timing *dvo_timing;

        dvo_timing = get_lvds_dvo_timing(lvds_lfp_data,
                         lvds_lfp_data_ptrs,
                         i);
        if (lvds_dvo_timing_equal_size(dvo_timing, panel_dvo_timing) &&
            dvo_timing->clock < downclock)
            downclock = dvo_timing->clock;
    }

    if (downclock < panel_dvo_timing->clock && i915_lvds_downclock) {
        dev_priv->lvds_downclock_avail = 1;
        dev_priv->lvds_downclock = downclock * 10;
        DRM_DEBUG_KMS("LVDS downclock is found in VBT. "
                  "Normal Clock %dKHz, downclock %dKHz\n",
                  panel_fixed_mode->clock, 10*downclock);
    }

    fp_timing = get_lvds_fp_timing(bdb, lvds_lfp_data,
                       lvds_lfp_data_ptrs,
                       lvds_options->panel_type);
    if (fp_timing) {
        /* check the resolution, just to be sure */
        if (fp_timing->x_res == panel_fixed_mode->hdisplay &&
            fp_timing->y_res == panel_fixed_mode->vdisplay) {
            dev_priv->bios_lvds_val = fp_timing->lvds_reg_val;
            DRM_DEBUG_KMS("VBT initial LVDS value %x\n",
                      dev_priv->bios_lvds_val);
        }
    }
}

/* Try to find sdvo panel data */
static void
parse_sdvo_panel_data(struct drm_i915_private *dev_priv,
              struct bdb_header *bdb)
{
    struct lvds_dvo_timing *dvo_timing;
    struct drm_display_mode *panel_fixed_mode;
    int index;

    index = i915_vbt_sdvo_panel_type;
    if (index == -2) {
        DRM_DEBUG_KMS("Ignore SDVO panel mode from BIOS VBT tables.\n");
        return;
    }

    if (index == -1) {
        struct bdb_sdvo_lvds_options *sdvo_lvds_options;

        sdvo_lvds_options = find_section(bdb, BDB_SDVO_LVDS_OPTIONS);
        if (!sdvo_lvds_options)
            return;

        index = sdvo_lvds_options->panel_type;
    }

    dvo_timing = find_section(bdb, BDB_SDVO_PANEL_DTDS);
    if (!dvo_timing)
        return;

    panel_fixed_mode = kzalloc(sizeof(*panel_fixed_mode), GFP_KERNEL);
    if (!panel_fixed_mode)
        return;

    fill_detail_timing_data(panel_fixed_mode, dvo_timing + index);

    dev_priv->sdvo_lvds_vbt_mode = panel_fixed_mode;

    DRM_DEBUG_KMS("Found SDVO panel mode in BIOS VBT tables:\n");
    drm_mode_debug_printmodeline(panel_fixed_mode);
}

static int intel_bios_ssc_frequency(struct drm_device *dev,
                    bool alternate)
{
    switch (INTEL_INFO(dev)->gen) {
    case 2:
        return alternate ? 66 : 48;
    case 3:
    case 4:
        return alternate ? 100 : 96;
    default:
        return alternate ? 100 : 120;
    }
}

static void
parse_general_features(struct drm_i915_private *dev_priv,
               struct bdb_header *bdb)
{
    struct drm_device *dev = dev_priv->dev;
    struct bdb_general_features *general;

    general = find_section(bdb, BDB_GENERAL_FEATURES);
    if (general) {
        dev_priv->int_tv_support = general->int_tv_support;
        dev_priv->int_crt_support = general->int_crt_support;
        dev_priv->lvds_use_ssc = general->enable_ssc;
        dev_priv->lvds_ssc_freq =
            intel_bios_ssc_frequency(dev, general->ssc_freq);
        dev_priv->display_clock_mode = general->display_clock_mode;
        DRM_DEBUG_KMS("BDB_GENERAL_FEATURES int_tv_support %d int_crt_support %d lvds_use_ssc %d lvds_ssc_freq %d display_clock_mode %d\n",
                  dev_priv->int_tv_support,
                  dev_priv->int_crt_support,
                  dev_priv->lvds_use_ssc,
                  dev_priv->lvds_ssc_freq,
                  dev_priv->display_clock_mode);
    }
}

static void
parse_general_definitions(struct drm_i915_private *dev_priv,
              struct bdb_header *bdb)
{
    struct bdb_general_definitions *general;

    general = find_section(bdb, BDB_GENERAL_DEFINITIONS);
    if (general) {
        u16 block_size = get_blocksize(general);
        if (block_size >= sizeof(*general)) {
            int bus_pin = general->crt_ddc_gmbus_pin;
            DRM_DEBUG_KMS("crt_ddc_bus_pin: %d\n", bus_pin);
            if (intel_gmbus_is_port_valid(bus_pin))
                dev_priv->crt_ddc_pin = bus_pin;
        } else {
            DRM_DEBUG_KMS("BDB_GD too small (%d). Invalid.\n",
                      block_size);
        }
    }
}

static void
parse_sdvo_device_mapping(struct drm_i915_private *dev_priv,
              struct bdb_header *bdb)
{
    struct sdvo_device_mapping *p_mapping;
    struct bdb_general_definitions *p_defs;
    struct child_device_config *p_child;
    int i, child_device_num, count;
    u16 block_size;

    p_defs = find_section(bdb, BDB_GENERAL_DEFINITIONS);
    if (!p_defs) {
        DRM_DEBUG_KMS("No general definition block is found, unable to construct sdvo mapping.\n");
        return;
    }
    /* judge whether the size of child device meets the requirements.
     * If the child device size obtained from general definition block
     * is different with sizeof(struct child_device_config), skip the
     * parsing of sdvo device info
     */
    if (p_defs->child_dev_size != sizeof(*p_child)) {
        /* different child dev size . Ignore it */
        DRM_DEBUG_KMS("different child size is found. Invalid.\n");
        return;
    }
    /* get the block size of general definitions */
    block_size = get_blocksize(p_defs);
    /* get the number of child device */
    child_device_num = (block_size - sizeof(*p_defs)) /
                sizeof(*p_child);
    count = 0;
    for (i = 0; i < child_device_num; i++) {
        p_child = &(p_defs->devices[i]);
        if (!p_child->device_type) {
            /* skip the device block if device type is invalid */
            continue;
        }
        if (p_child->slave_addr != SLAVE_ADDR1 &&
            p_child->slave_addr != SLAVE_ADDR2) {
            /*
             * If the slave address is neither 0x70 nor 0x72,
             * it is not a SDVO device. Skip it.
             */
            continue;
        }
        if (p_child->dvo_port != DEVICE_PORT_DVOB &&
            p_child->dvo_port != DEVICE_PORT_DVOC) {
            /* skip the incorrect SDVO port */
            DRM_DEBUG_KMS("Incorrect SDVO port. Skip it\n");
            continue;
        }
        DRM_DEBUG_KMS("the SDVO device with slave addr %2x is found on"
                " %s port\n",
                p_child->slave_addr,
                (p_child->dvo_port == DEVICE_PORT_DVOB) ?
                    "SDVOB" : "SDVOC");
        p_mapping = &(dev_priv->sdvo_mappings[p_child->dvo_port - 1]);
        if (!p_mapping->initialized) {
            p_mapping->dvo_port = p_child->dvo_port;
            p_mapping->slave_addr = p_child->slave_addr;
            p_mapping->dvo_wiring = p_child->dvo_wiring;
            p_mapping->ddc_pin = p_child->ddc_pin;
            p_mapping->i2c_pin = p_child->i2c_pin;
            p_mapping->initialized = 1;
            DRM_DEBUG_KMS("SDVO device: dvo=%x, addr=%x, wiring=%d, ddc_pin=%d, i2c_pin=%d\n",
                      p_mapping->dvo_port,
                      p_mapping->slave_addr,
                      p_mapping->dvo_wiring,
                      p_mapping->ddc_pin,
                      p_mapping->i2c_pin);
        } else {
            DRM_DEBUG_KMS("Maybe one SDVO port is shared by "
                     "two SDVO device.\n");
        }
        if (p_child->slave2_addr) {
            /* Maybe this is a SDVO device with multiple inputs */
            /* And the mapping info is not added */
            DRM_DEBUG_KMS("there exists the slave2_addr. Maybe this"
                " is a SDVO device with multiple inputs.\n");
        }
        count++;
    }

    if (!count) {
        /* No SDVO device info is found */
        DRM_DEBUG_KMS("No SDVO device info is found in VBT\n");
    }
    return;
}

static void
parse_driver_features(struct drm_i915_private *dev_priv,
               struct bdb_header *bdb)
{
    struct drm_device *dev = dev_priv->dev;
    struct bdb_driver_features *driver;

    driver = find_section(bdb, BDB_DRIVER_FEATURES);
    if (!driver)
        return;

    if (SUPPORTS_EDP(dev) &&
        driver->lvds_config == BDB_DRIVER_FEATURE_EDP)
        dev_priv->edp.support = 1;

    if (driver->dual_frequency)
        dev_priv->render_reclock_avail = true;
}

static void
parse_edp(struct drm_i915_private *dev_priv, struct bdb_header *bdb)
{
    struct bdb_edp *edp;
    struct edp_power_seq *edp_pps;
    struct edp_link_params *edp_link_params;

    edp = find_section(bdb, BDB_EDP);
    if (!edp) {
        if (SUPPORTS_EDP(dev_priv->dev) && dev_priv->edp.support)
            DRM_DEBUG_KMS("No eDP BDB found but eDP panel supported.\n");
        return;
    }

    switch ((edp->color_depth >> (panel_type * 2)) & 3) {
    case EDP_18BPP:
        dev_priv->edp.bpp = 18;
        break;
    case EDP_24BPP:
        dev_priv->edp.bpp = 24;
        break;
    case EDP_30BPP:
        dev_priv->edp.bpp = 30;
        break;
    }

    /* Get the eDP sequencing and link info */
    edp_pps = &edp->power_seqs[panel_type];
    edp_link_params = &edp->link_params[panel_type];

    dev_priv->edp.pps = *edp_pps;

    dev_priv->edp.rate = edp_link_params->rate ? DP_LINK_BW_2_7 :
        DP_LINK_BW_1_62;
    switch (edp_link_params->lanes) {
    case 0:
        dev_priv->edp.lanes = 1;
        break;
    case 1:
        dev_priv->edp.lanes = 2;
        break;
    case 3:
    default:
        dev_priv->edp.lanes = 4;
        break;
    }
    switch (edp_link_params->preemphasis) {
    case 0:
        dev_priv->edp.preemphasis = DP_TRAIN_PRE_EMPHASIS_0;
        break;
    case 1:
        dev_priv->edp.preemphasis = DP_TRAIN_PRE_EMPHASIS_3_5;
        break;
    case 2:
        dev_priv->edp.preemphasis = DP_TRAIN_PRE_EMPHASIS_6;
        break;
    case 3:
        dev_priv->edp.preemphasis = DP_TRAIN_PRE_EMPHASIS_9_5;
        break;
    }
    switch (edp_link_params->vswing) {
    case 0:
        dev_priv->edp.vswing = DP_TRAIN_VOLTAGE_SWING_400;
        break;
    case 1:
        dev_priv->edp.vswing = DP_TRAIN_VOLTAGE_SWING_600;
        break;
    case 2:
        dev_priv->edp.vswing = DP_TRAIN_VOLTAGE_SWING_800;
        break;
    case 3:
        dev_priv->edp.vswing = DP_TRAIN_VOLTAGE_SWING_1200;
        break;
    }
}

static void
parse_device_mapping(struct drm_i915_private *dev_priv,
               struct bdb_header *bdb)
{
    struct bdb_general_definitions *p_defs;
    struct child_device_config *p_child, *child_dev_ptr;
    int i, child_device_num, count;
    u16 block_size;

    p_defs = find_section(bdb, BDB_GENERAL_DEFINITIONS);
    if (!p_defs) {
        DRM_DEBUG_KMS("No general definition block is found, no devices defined.\n");
        return;
    }
    /* judge whether the size of child device meets the requirements.
     * If the child device size obtained from general definition block
     * is different with sizeof(struct child_device_config), skip the
     * parsing of sdvo device info
     */
    if (p_defs->child_dev_size != sizeof(*p_child)) {
        /* different child dev size . Ignore it */
        DRM_DEBUG_KMS("different child size is found. Invalid.\n");
        return;
    }
    /* get the block size of general definitions */
    block_size = get_blocksize(p_defs);
    /* get the number of child device */
    child_device_num = (block_size - sizeof(*p_defs)) /
                sizeof(*p_child);
    count = 0;
    /* get the number of child device that is present */
    for (i = 0; i < child_device_num; i++) {
        p_child = &(p_defs->devices[i]);
        if (!p_child->device_type) {
            /* skip the device block if device type is invalid */
            continue;
        }
        count++;
    }
    if (!count) {
        DRM_DEBUG_KMS("no child dev is parsed from VBT\n");
        return;
    }
    dev_priv->child_dev = kcalloc(count, sizeof(*p_child), GFP_KERNEL);
    if (!dev_priv->child_dev) {
        DRM_DEBUG_KMS("No memory space for child device\n");
        return;
    }

    dev_priv->child_dev_num = count;
    count = 0;
    for (i = 0; i < child_device_num; i++) {
        p_child = &(p_defs->devices[i]);
        if (!p_child->device_type) {
            /* skip the device block if device type is invalid */
            continue;
        }
        child_dev_ptr = dev_priv->child_dev + count;
        count++;
        memcpy((void *)child_dev_ptr, (void *)p_child,
                    sizeof(*p_child));
    }
    return;
}

static void
init_vbt_defaults(struct drm_i915_private *dev_priv)
{
    struct drm_device *dev = dev_priv->dev;

    dev_priv->crt_ddc_pin = GMBUS_PORT_VGADDC;

    /* LFP panel data */
    dev_priv->lvds_dither = 1;
    dev_priv->lvds_vbt = 0;

    /* SDVO panel data */
    dev_priv->sdvo_lvds_vbt_mode = NULL;

    /* general features */
    dev_priv->int_tv_support = 1;
    dev_priv->int_crt_support = 1;

    /* Default to using SSC */
    dev_priv->lvds_use_ssc = 1;
    dev_priv->lvds_ssc_freq = intel_bios_ssc_frequency(dev, 1);
    DRM_DEBUG_KMS("Set default to SSC at %dMHz\n", dev_priv->lvds_ssc_freq);
}

static int __init intel_no_opregion_vbt_callback(const struct dmi_system_id *id)
{
    DRM_DEBUG_KMS("Falling back to manually reading VBT from "
              "VBIOS ROM for %s\n",
              id->ident);
    return 1;
}

static const struct dmi_system_id intel_no_opregion_vbt[] = {
    {
        .callback = intel_no_opregion_vbt_callback,
        .ident = "ThinkCentre A57",
        .matches = {
            DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
            DMI_MATCH(DMI_PRODUCT_NAME, "97027RG"),
        },
    },
    { }
};

int
intel_parse_bios(struct drm_device *dev)
{
    struct drm_i915_private *dev_priv = dev->dev_private;
    struct pci_dev *pdev = dev->pdev;
    struct bdb_header *bdb = NULL;
    u8 __iomem *bios = NULL;

    init_vbt_defaults(dev_priv);

    /* XXX Should this validation be moved to intel_opregion.c? */
    if (!dmi_check_system(intel_no_opregion_vbt) && dev_priv->opregion.vbt) {
        struct vbt_header *vbt = dev_priv->opregion.vbt;
        if (memcmp(vbt->signature, "$VBT", 4) == 0) {
            DRM_DEBUG_KMS("Using VBT from OpRegion: %20s\n",
                     vbt->signature);
            bdb = (struct bdb_header *)((char *)vbt + vbt->bdb_offset);
        } else
            dev_priv->opregion.vbt = NULL;
    }

    if (bdb == NULL) {
        struct vbt_header *vbt = NULL;
        size_t size;
        int i;

        bios = pci_map_rom(pdev, &size);
        if (!bios)
            return -1;

        /* Scour memory looking for the VBT signature */
        for (i = 0; i + 4 < size; i++) {
            if (!memcmp(bios + i, "$VBT", 4)) {
                vbt = (struct vbt_header *)(bios + i);
                break;
            }
        }

        if (!vbt) {
            DRM_DEBUG_DRIVER("VBT signature missing\n");
            pci_unmap_rom(pdev, bios);
            return -1;
        }

        bdb = (struct bdb_header *)(bios + i + vbt->bdb_offset);
    }

    /* Grab useful general definitions */
    parse_general_features(dev_priv, bdb);
    parse_general_definitions(dev_priv, bdb);
    parse_lfp_panel_data(dev_priv, bdb);
    parse_sdvo_panel_data(dev_priv, bdb);
    parse_sdvo_device_mapping(dev_priv, bdb);
    parse_device_mapping(dev_priv, bdb);
    parse_driver_features(dev_priv, bdb);
    parse_edp(dev_priv, bdb);

    if (bios)
        pci_unmap_rom(pdev, bios);

    return 0;
}

/* Ensure that vital registers have been initialised, even if the BIOS
 * is absent or just failing to do its job.
 */
void intel_setup_bios(struct drm_device *dev)
{
    struct drm_i915_private *dev_priv = dev->dev_private;

     /* Set the Panel Power On/Off timings if uninitialized. */
    if ((I915_READ(PP_ON_DELAYS) == 0) && (I915_READ(PP_OFF_DELAYS) == 0)) {
        /* Set T2 to 40ms and T5 to 200ms */
        I915_WRITE(PP_ON_DELAYS, 0x019007d0);

        /* Set T3 to 35ms and Tx to 200ms */
        I915_WRITE(PP_OFF_DELAYS, 0x015e07d0);
    }
}