On Wed, 06 Apr 2022, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Modern VBTs no longer contain the LFP data table pointers
> block (41). We are expecting to have one in order to be able
> to parse the LFP data block (42), so let's make one up.
Bspec says, "These fields are used by the BMP tool to locate the tables
in block 42 and present in its GUI."
Sounds like an alternative would be to always just parse block 42
directly instead of validating/generating block 41 for that?
Maybe it's easier to go with what you've done here now, and reconsider
in the future. *shrug*.
BR,
Jani.
>
> Since the fp_timing table has variable size we must somehow
> determine its size. Rather than just hardcode it we look for
> the terminator bytes (0xffff) to figure out where each table
> entry starts. dvo_timing, panel_pnp_id, and panel_name are
> expected to have fixed size.
>
> This has been observed on various machines, eg. TGL with BDB
> version 240, CML with BDB version 231, etc. The most recent
> VBT I've observed that still had block 41 had BDB version
> 228. So presumably the cutoff (if an exact cutoff even exists)
> is somewhere around BDB version 229-231.
>
> v2: kfree the thing we allocated, not the thing+3 bytes
> v3: Do the debugprint only if we found the LFP data block
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_bios.c | 136 +++++++++++++++++++++-
> 1 file changed, 135 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index 8b118c54314d..d32091dad1b0 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -310,16 +310,146 @@ static bool fixup_lfp_data_ptrs(const void *bdb, void *ptrs_block)
> return validate_lfp_data_ptrs(bdb, ptrs);
> }
>
> +static const void *find_fp_timing_terminator(const u8 *data, int size)
> +{
> + int i;
> +
> + if (!data)
> + return NULL;
> +
> + for (i = 0; i < size - 1; i++) {
> + if (data[i] == 0xff && data[i+1] == 0xff)
> + return &data[i];
> + }
> +
> + return NULL;
> +}
> +
> +static int make_lfp_data_ptr(struct lvds_lfp_data_ptr_table *table,
> + int table_size, int total_size)
> +{
> + if (total_size < table_size)
> + return total_size;
> +
> + table->table_size = table_size;
> + table->offset = total_size - table_size;
> +
> + return total_size - table_size;
> +}
> +
> +static void next_lfp_data_ptr(struct lvds_lfp_data_ptr_table *next,
> + const struct lvds_lfp_data_ptr_table *prev,
> + int size)
> +{
> + next->table_size = prev->table_size;
> + next->offset = prev->offset + size;
> +}
> +
> +static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
> + const void *bdb)
> +{
> + int i, size, table_size, block_size, offset;
> + const void *t0, *t1, *block;
> + struct bdb_lvds_lfp_data_ptrs *ptrs;
> + void *ptrs_block;
> +
> + block = find_raw_section(bdb, BDB_LVDS_LFP_DATA);
> + if (!block)
> + return NULL;
> +
> + drm_dbg_kms(&i915->drm, "Generating LFP data table pointers\n");
> +
> + block_size = get_blocksize(block);
> +
> + size = block_size;
> + t0 = find_fp_timing_terminator(block, size);
> +
> + size -= t0 - block - 2;
> + t1 = find_fp_timing_terminator(t0 + 2, size);
> +
> + if (!t0 || !t1)
> + return NULL;
> +
> + size = t1 - t0;
> + if (size * 16 > block_size)
> + return NULL;
> +
> + ptrs_block = kzalloc(sizeof(*ptrs) + 3, GFP_KERNEL);
> + if (!ptrs_block)
> + return NULL;
> +
> + *(u8 *)(ptrs_block + 0) = BDB_LVDS_LFP_DATA_PTRS;
> + *(u16 *)(ptrs_block + 1) = sizeof(*ptrs);
> + ptrs = ptrs_block + 3;
> +
> + table_size = sizeof(struct lvds_pnp_id);
> + size = make_lfp_data_ptr(&ptrs->ptr[0].panel_pnp_id, table_size, size);
> +
> + table_size = sizeof(struct lvds_dvo_timing);
> + size = make_lfp_data_ptr(&ptrs->ptr[0].dvo_timing, table_size, size);
> +
> + table_size = t0 - block + 2;
> + size = make_lfp_data_ptr(&ptrs->ptr[0].fp_timing, table_size, size);
> +
> + if (ptrs->ptr[0].fp_timing.table_size)
> + ptrs->lvds_entries++;
> + if (ptrs->ptr[0].dvo_timing.table_size)
> + ptrs->lvds_entries++;
> + if (ptrs->ptr[0].panel_pnp_id.table_size)
> + ptrs->lvds_entries++;
> +
> + if (size != 0 || ptrs->lvds_entries != 3) {
> + kfree(ptrs);
> + return NULL;
> + }
> +
> + size = t1 - t0;
> + for (i = 1; i < 16; i++) {
> + next_lfp_data_ptr(&ptrs->ptr[i].fp_timing, &ptrs->ptr[i-1].fp_timing, size);
> + next_lfp_data_ptr(&ptrs->ptr[i].dvo_timing, &ptrs->ptr[i-1].dvo_timing, size);
> + next_lfp_data_ptr(&ptrs->ptr[i].panel_pnp_id, &ptrs->ptr[i-1].panel_pnp_id, size);
> + }
> +
> + size = t1 - t0;
> + table_size = sizeof(struct lvds_lfp_panel_name);
> +
> + if (16 * (size + table_size) <= block_size) {
> + ptrs->panel_name.table_size = table_size;
> + ptrs->panel_name.offset = size * 16;
> + }
> +
> + offset = block - bdb;
> +
> + for (i = 0; i < 16; i++) {
> + ptrs->ptr[i].fp_timing.offset += offset;
> + ptrs->ptr[i].dvo_timing.offset += offset;
> + ptrs->ptr[i].panel_pnp_id.offset += offset;
> + }
> +
> + if (ptrs->panel_name.table_size)
> + ptrs->panel_name.offset += offset;
> +
> + return ptrs_block;
> +}
> +
> static void
> init_bdb_block(struct drm_i915_private *i915,
> const void *bdb, enum bdb_block_id section_id,
> size_t min_size)
> {
> struct bdb_block_entry *entry;
> + void *temp_block = NULL;
> const void *block;
> size_t block_size;
>
> block = find_raw_section(bdb, section_id);
> +
> + /* Modern VBTs lack the LFP data table pointers block, make one up */
> + if (!block && section_id == BDB_LVDS_LFP_DATA_PTRS) {
> + temp_block = generate_lfp_data_ptrs(i915, bdb);
> + if (temp_block)
> + block = temp_block + 3;
> + }
> if (!block)
> return;
>
> @@ -330,12 +460,16 @@ init_bdb_block(struct drm_i915_private *i915,
>
> entry = kzalloc(struct_size(entry, data, max(min_size, block_size) + 3),
> GFP_KERNEL);
> - if (!entry)
> + if (!entry) {
> + kfree(temp_block);
> return;
> + }
>
> entry->section_id = section_id;
> memcpy(entry->data, block - 3, block_size + 3);
>
> + kfree(temp_block);
> +
> drm_dbg_kms(&i915->drm, "Found BDB block %d (size %zu, min size %zu)\n",
> section_id, block_size, min_size);
--
Jani Nikula, Intel Open Source Graphics Center
