On Thu, 17 Mar 2022, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Currently get_lvds_fp_timing() still returns a pointer to the original
> data block rather than our copy. Let's convert the data pointer offsets
> to be relative to the data block rather than the whole BDB. With that
> we can make get_lvds_fp_timing() return a pointer to the copy.
Ugh, so just as I R-b'd the previous patch... I realize it's all broken
without this, right? It does pointer arithmetics between bdb header and
the allocated bdb for ptrs?
Do we want a broken step?
BR,
Jani.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_bios.c | 56 ++++++++++++++++++++---
> 1 file changed, 49 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index ff04514eb3b7..777339f5dd79 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -138,6 +138,44 @@ find_raw_section(const void *_bdb, enum bdb_block_id section_id)
> return NULL;
> }
>
> +/*
> + * Offset from the start of BDB to the start of the
> + * block data (just past the block header).
> + */
> +static u32 block_offset(const void *bdb, enum bdb_block_id section_id)
> +{
> + const void *block;
> +
> + block = find_raw_section(bdb, section_id);
> + if (!block)
> + return 0;
> +
> + return block - bdb;
> +}
> +
> +/* make the data table offsets relative to the data block */
> +static bool fixup_lfp_data_ptrs(const void *bdb, void *ptrs_block)
> +{
> + struct bdb_lvds_lfp_data_ptrs *ptrs = ptrs_block;
> + u32 offset;
> + int i;
> +
> + offset = block_offset(bdb, BDB_LVDS_LFP_DATA);
> +
> + for (i = 0; i < 16; i++) {
> + if (ptrs->ptr[i].fp_timing.offset < offset ||
> + ptrs->ptr[i].dvo_timing.offset < offset ||
> + ptrs->ptr[i].panel_pnp_id.offset < offset)
> + return false;
> +
> + ptrs->ptr[i].fp_timing.offset -= offset;
> + ptrs->ptr[i].dvo_timing.offset -= offset;
> + ptrs->ptr[i].panel_pnp_id.offset -= offset;
> + }
> +
> + return true;
> +}
> +
> static const void *
> find_section(struct drm_i915_private *i915,
> const void *bdb, enum bdb_block_id section_id,
> @@ -174,6 +212,13 @@ find_section(struct drm_i915_private *i915,
> drm_dbg_kms(&i915->drm, "Found BDB block %d (size %zu, min size %zu)\n",
> section_id, block_size, min_size);
>
> + if (section_id == BDB_LVDS_LFP_DATA_PTRS &&
> + !fixup_lfp_data_ptrs(bdb, entry->data + 3)) {
> + drm_err(&i915->drm, "VBT has malformed LFP data table pointers\n");
> + kfree(entry);
> + return NULL;
> + }
> +
> list_add(&entry->node, &i915->vbt.bdb_blocks);
>
> return entry->data + 3;
> @@ -255,22 +300,19 @@ get_lvds_dvo_timing(const struct bdb_lvds_lfp_data *lvds_lfp_data,
> * 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,
> +get_lvds_fp_timing(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)
> + if (ofs + sizeof(struct lvds_fp_timing) > data_size)
> return NULL;
> - return (const struct lvds_fp_timing *)((const u8 *)bdb + ofs);
> + return (const struct lvds_fp_timing *)((const u8 *)data + ofs);
> }
>
> /* Parse general panel options */
> @@ -373,7 +415,7 @@ parse_lfp_panel_dtd(struct drm_i915_private *i915,
> "Found panel mode in BIOS VBT legacy lfp table:\n");
> drm_mode_debug_printmodeline(panel_fixed_mode);
>
> - fp_timing = get_lvds_fp_timing(bdb, lvds_lfp_data,
> + fp_timing = get_lvds_fp_timing(lvds_lfp_data,
> lvds_lfp_data_ptrs,
> panel_type);
> if (fp_timing) {
--
Jani Nikula, Intel Open Source Graphics Center
