From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> Older VBTs don't have all the stuff we've defined for the LVDS options block (40). In particular we're currently parsing the DPS panel type bits even though they may not exist, which could mean we end up flagging the machine as supporting static DRRS when the VBT declared no such thing. We don't actually have a clear idea which VBT versions have which bits so we rely on the block size instead. Here's a quick list from my VBT stash: mgm version 108 -> 4 bytes alv version 120 -> 4 bytes cst version 134 -> 14 bytes pnv version 144 -> 14 bytes cl version 142 -> 16 bytes ctg version 155 -> 24 bytes Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/display/intel_bios.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c index df52f406e1ae..807184fd5618 100644 --- a/drivers/gpu/drm/i915/display/intel_bios.c +++ b/drivers/gpu/drm/i915/display/intel_bios.c @@ -758,6 +758,14 @@ parse_panel_options(struct drm_i915_private *i915, panel->vbt.lvds_dither = lvds_options->pixel_dither; + /* + * Empirical evidence indicates the block size can be + * either 4,14,16,24+ bytes. For older VBTs no clear + * relationship between the block size vs. BDB version. + */ + if (get_blocksize(lvds_options) < 16) + return; + drrs_mode = (lvds_options->dps_panel_type_bits >> (panel_type * 2)) & MODE_MASK; /* -- 2.35.1
