On Fri, Sep 02, 2022 at 01:47:14PM +0300, Jani Nikula wrote:
> 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.
Not sure how much it would help. I suspect one still ends
up decoding the whole hexdump by hand.
>
> 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
--
Ville Syrjälä
Intel
