Ville pointed this out to me when fixing some issues in drm_dp_read_downstream_info() - the DPCD version check here is bogus as there's no DisplayPort versions prior to 1.0. The original code from i915 that this was extracted from actually did:
dpcd[DP_DPCD_REV] == DP_DPCD_REV_10
Which is correct, and somehow got missed when extracting this function. So let's fix this. Note that as far as I'm aware, I don't think this fixes any actual issues users are hitting.
Signed-off-by: Lyude Paul lyude@redhat.com Cc: Ville Syrjälä ville.syrjala@linux.intel.com --- drivers/gpu/drm/drm_dp_helper.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 0f84df8798ab..55b53df6ce34 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -677,7 +677,7 @@ int drm_dp_read_downstream_info(struct drm_dp_aux *aux, memset(downstream_ports, 0, DP_MAX_DOWNSTREAM_PORTS);
/* No downstream info to read */ - if (!drm_dp_is_branch(dpcd) || dpcd[DP_DPCD_REV] < DP_DPCD_REV_10) + if (!drm_dp_is_branch(dpcd) || dpcd[DP_DPCD_REV] == DP_DPCD_REV_10) return 0;
/* Some branches advertise having 0 downstream ports, despite also advertising they have a