On Thu, 18 Aug 2022, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Validate the LFP data block a bit hardwer by making sure the
> fp_timing terminators (0xffff) are where we expect them to be.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
I wonder if it would be good to debug log at each of the "return false"
sites in fixup_lfp_data_ptrs() and validate_lfp_data_ptrs(). Anyway,
that's a separate change.
Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_bios.c | 60 ++++++++++++-----------
> 1 file changed, 32 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index 198a2f4920cc..f1f861da9e93 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -135,18 +135,6 @@ static u32 raw_block_offset(const void *bdb, enum bdb_block_id section_id)
> return block - bdb;
> }
>
> -/* size of the block excluding the header */
> -static u32 raw_block_size(const void *bdb, enum bdb_block_id section_id)
> -{
> - const void *block;
> -
> - block = find_raw_section(bdb, section_id);
> - if (!block)
> - return 0;
> -
> - return get_blocksize(block);
> -}
> -
> struct bdb_block_entry {
> struct list_head node;
> enum bdb_block_id section_id;
> @@ -231,9 +219,14 @@ static bool validate_lfp_data_ptrs(const void *bdb,
> {
> int fp_timing_size, dvo_timing_size, panel_pnp_id_size, panel_name_size;
> int data_block_size, lfp_data_size;
> + const void *data_block;
> int i;
>
> - data_block_size = raw_block_size(bdb, BDB_LVDS_LFP_DATA);
> + data_block = find_raw_section(bdb, BDB_LVDS_LFP_DATA);
> + if (!data_block)
> + return false;
> +
> + data_block_size = get_blocksize(data_block);
> if (data_block_size == 0)
> return false;
>
> @@ -261,21 +254,6 @@ static bool validate_lfp_data_ptrs(const void *bdb,
> if (16 * lfp_data_size > data_block_size)
> return false;
>
> - /*
> - * Except for vlv/chv machines all real VBTs seem to have 6
> - * unaccounted bytes in the fp_timing table. And it doesn't
> - * appear to be a really intentional hole as the fp_timing
> - * 0xffff terminator is always within those 6 missing bytes.
> - */
> - if (fp_timing_size + dvo_timing_size + panel_pnp_id_size != lfp_data_size &&
> - fp_timing_size + 6 + dvo_timing_size + panel_pnp_id_size != lfp_data_size)
> - return false;
> -
> - if (ptrs->ptr[0].fp_timing.offset + fp_timing_size > ptrs->ptr[0].dvo_timing.offset ||
> - ptrs->ptr[0].dvo_timing.offset + dvo_timing_size != ptrs->ptr[0].panel_pnp_id.offset ||
> - ptrs->ptr[0].panel_pnp_id.offset + panel_pnp_id_size != lfp_data_size)
> - return false;
> -
> /* make sure the table entries have uniform size */
> for (i = 1; i < 16; i++) {
> if (ptrs->ptr[i].fp_timing.table_size != fp_timing_size ||
> @@ -289,6 +267,23 @@ static bool validate_lfp_data_ptrs(const void *bdb,
> return false;
> }
>
> + /*
> + * Except for vlv/chv machines all real VBTs seem to have 6
> + * unaccounted bytes in the fp_timing table. And it doesn't
> + * appear to be a really intentional hole as the fp_timing
> + * 0xffff terminator is always within those 6 missing bytes.
> + */
> + if (fp_timing_size + 6 + dvo_timing_size + panel_pnp_id_size == lfp_data_size)
> + fp_timing_size += 6;
> +
> + if (fp_timing_size + dvo_timing_size + panel_pnp_id_size != lfp_data_size)
> + return false;
> +
> + if (ptrs->ptr[0].fp_timing.offset + fp_timing_size != ptrs->ptr[0].dvo_timing.offset ||
> + ptrs->ptr[0].dvo_timing.offset + dvo_timing_size != ptrs->ptr[0].panel_pnp_id.offset ||
> + ptrs->ptr[0].panel_pnp_id.offset + panel_pnp_id_size != lfp_data_size)
> + return false;
> +
> /* make sure the tables fit inside the data block */
> for (i = 0; i < 16; i++) {
> if (ptrs->ptr[i].fp_timing.offset + fp_timing_size > data_block_size ||
> @@ -300,6 +295,15 @@ static bool validate_lfp_data_ptrs(const void *bdb,
> if (ptrs->panel_name.offset + 16 * panel_name_size > data_block_size)
> return false;
>
> + /* make sure fp_timing terminators are present at expected locations */
> + for (i = 0; i < 16; i++) {
> + const u16 *t = data_block + ptrs->ptr[i].fp_timing.offset +
> + fp_timing_size - 2;
> +
> + if (*t != 0xffff)
> + return false;
> + }
> +
> return true;
> }
--
Jani Nikula, Intel Open Source Graphics Center
