| Message ID | 20210507214209.554866-1-lyude@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/dp: Fix bogus DPCD version check in drm_dp_read_downstream_info() | expand |
On Fri, May 07, 2021 at 05:42:09PM -0400, Lyude Paul wrote: > 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> Reviewed-by: 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 > -- > 2.30.2
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
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(-)