drm/i915/bios: Trust the LFP data pointers

Now that we've sufficiently validated the LFP data pointers we
can trust them.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220405173410.11436-6-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index de1c4be..762acf8 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -397,44 +397,19 @@ fill_detail_timing_data(struct drm_display_mode *panel_fixed_mode,
 }
 
 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,
+get_lvds_dvo_timing(const struct bdb_lvds_lfp_data *data,
+                   const struct bdb_lvds_lfp_data_ptrs *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);
+       return (const void *)data + ptrs->ptr[index].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_lvds_lfp_data *data,
                   const struct bdb_lvds_lfp_data_ptrs *ptrs,
                   int index)
 {
-       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 + sizeof(struct lvds_fp_timing) > data_size)
-               return NULL;
-       return (const struct lvds_fp_timing *)((const u8 *)data + ofs);
+       return (const void *)data + ptrs->ptr[index].fp_timing.offset;
 }
 
 /* Parse general panel options */
@@ -499,8 +474,7 @@ parse_panel_options(struct drm_i915_private *i915)
 
 /* Try to find integrated panel timing data */
 static void
-parse_lfp_panel_dtd(struct drm_i915_private *i915,
-                   const struct bdb_header *bdb)
+parse_lfp_panel_dtd(struct drm_i915_private *i915)
 {
        const struct bdb_lvds_lfp_data *lvds_lfp_data;
        const struct bdb_lvds_lfp_data_ptrs *lvds_lfp_data_ptrs;
@@ -536,15 +510,14 @@ parse_lfp_panel_dtd(struct drm_i915_private *i915,
        fp_timing = get_lvds_fp_timing(lvds_lfp_data,
                                       lvds_lfp_data_ptrs,
                                       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) {
-                       i915->vbt.bios_lvds_val = fp_timing->lvds_reg_val;
-                       drm_dbg_kms(&i915->drm,
-                                   "VBT initial LVDS value %x\n",
-                                   i915->vbt.bios_lvds_val);
-               }
+
+       /* check the resolution, just to be sure */
+       if (fp_timing->x_res == panel_fixed_mode->hdisplay &&
+           fp_timing->y_res == panel_fixed_mode->vdisplay) {
+               i915->vbt.bios_lvds_val = fp_timing->lvds_reg_val;
+               drm_dbg_kms(&i915->drm,
+                           "VBT initial LVDS value %x\n",
+                           i915->vbt.bios_lvds_val);
        }
 }
 
@@ -627,8 +600,7 @@ parse_generic_dtd(struct drm_i915_private *i915)
 }
 
 static void
-parse_panel_dtd(struct drm_i915_private *i915,
-               const struct bdb_header *bdb)
+parse_panel_dtd(struct drm_i915_private *i915)
 {
        /*
         * Older VBTs provided provided DTD information for internal displays
@@ -641,7 +613,7 @@ parse_panel_dtd(struct drm_i915_private *i915,
        if (i915->vbt.version >= 229)
                parse_generic_dtd(i915);
        if (!i915->vbt.lfp_lvds_vbt_mode)
-               parse_lfp_panel_dtd(i915, bdb);
+               parse_lfp_panel_dtd(i915);
 }
 
 static void
@@ -2720,7 +2692,7 @@ void intel_bios_init(struct drm_i915_private *i915)
        parse_general_features(i915);
        parse_general_definitions(i915);
        parse_panel_options(i915);
-       parse_panel_dtd(i915, bdb);
+       parse_panel_dtd(i915);
        parse_lfp_backlight(i915);
        parse_sdvo_panel_data(i915);
        parse_driver_features(i915);