On Fri, Sep 02, 2022 at 02:12:50PM +0300, Jani Nikula wrote: > On Thu, 18 Aug 2022, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > > The current scheme for generating the LFP data table pointers > > (when the block including them is missing from the VBT) expects > > the 0xffff sequence to only appear in the fp_timing terminator > > entries. However some VBTs also have extra 0xffff sequences > > elsewhere in the LFP data. When looking for the terminators > > we may end up finding those extra sequeneces insted, which means > > we deduce the wrong size for the fp_timing table. The code > > then notices the inconsistent looking values and gives up on > > the generated data table pointers, preventing us from parsing > > the LFP data table entirely. > > > > Let's give up on the "search for the terminators" approach > > and instead just hardcode the expected size for the fp_timing > > table. > > > > We have enough sanity checks in place to make sure we > > shouldn't end up parsing total garbage even if that size > > should change in the future (although that seems unlikely > > as the fp_timing and dvo_timing tables have been declared > > obsolete as of VBT version 229). > > > > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6592 > > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > What a mess. > > Could debug log about missing data ptrs on vbt version < 155, but no > biggie. I think we'd still end up tripping the WARN(min_size == 0) thing. Not the clearest warning I admit, but at least it shouldn't just silently ignore it. > > Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx> Thanks. > > > > --- > > drivers/gpu/drm/i915/display/intel_bios.c | 46 +++++++++-------------- > > 1 file changed, 18 insertions(+), 28 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c > > index f1f861da9e93..f54a1843924e 100644 > > --- a/drivers/gpu/drm/i915/display/intel_bios.c > > +++ b/drivers/gpu/drm/i915/display/intel_bios.c > > @@ -337,18 +337,6 @@ 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; > > - > > - 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) > > { > > @@ -372,11 +360,22 @@ static void next_lfp_data_ptr(struct lvds_lfp_data_ptr_table *next, > > 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; > > + int i, size, table_size, block_size, offset, fp_timing_size; > > struct bdb_lvds_lfp_data_ptrs *ptrs; > > + const void *block; > > void *ptrs_block; > > > > + /* > > + * The hardcoded fp_timing_size is only valid for > > + * modernish VBTs. All older VBTs definitely should > > + * include block 41 and thus we don't need to > > + * generate one. > > + */ > > + if (i915->vbt.version < 155) > > + return NULL; > > + > > + fp_timing_size = 38; > > + > > block = find_raw_section(bdb, BDB_LVDS_LFP_DATA); > > if (!block) > > return NULL; > > @@ -385,17 +384,8 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915, > > > > block_size = get_blocksize(block); > > > > - size = block_size; > > - t0 = find_fp_timing_terminator(block, size); > > - if (!t0) > > - return NULL; > > - > > - size -= t0 - block - 2; > > - t1 = find_fp_timing_terminator(t0 + 2, size); > > - if (!t1) > > - return NULL; > > - > > - size = t1 - t0; > > + size = fp_timing_size + sizeof(struct lvds_dvo_timing) + > > + sizeof(struct lvds_pnp_id); > > if (size * 16 > block_size) > > return NULL; > > > > @@ -413,7 +403,7 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915, > > 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; > > + table_size = fp_timing_size; > > size = make_lfp_data_ptr(&ptrs->ptr[0].fp_timing, table_size, size); > > > > if (ptrs->ptr[0].fp_timing.table_size) > > @@ -428,14 +418,14 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915, > > return NULL; > > } > > > > - size = t1 - t0; > > + size = fp_timing_size + sizeof(struct lvds_dvo_timing) + > > + sizeof(struct lvds_pnp_id); > > 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) { > > -- > Jani Nikula, Intel Open Source Graphics Center -- Ville Syrjälä Intel
