[PATCH 4.18 158/171] drm/i915: Skip vcpi allocation for MSTB ports that are gone

Greg Kroah-Hartman
2018-11-19T16:46:54Z

From: Lyude Paul <lyude@redhat.com>

commit c02ba4ef16eefe663fdefcccaa57fad32d5481bf upstream.

Since we need to be able to allow DPMS on->off prop changes after an MST
port has disappeared from the system, we need to be able to make sure we
can compute a config for the resulting atomic commit. Currently this is
impossible when the port has disappeared, since the VCPI slot searching
we try to do in intel_dp_mst_compute_config() will fail with -EINVAL.

Since the only commits we want to allow on no-longer-present MST ports
are ones that shut off display hardware, we already know that no VCPI
allocations are needed. So, hardcode the VCPI slot count to 0 when
intel_dp_mst_compute_config() is called on an MST port that's gone.

Changes since V4:
- Don't use mst_port_gone at all, just check whether or not the drm
connector is registered - Daniel Vetter

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20181008232437.5571-5-lyude@redhat.com
(cherry picked from commit f67207d78ceaf98b7531bc22df6f21328559c8d4)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/i915/intel_dp_mst.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)

--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -38,11 +38,11 @@ static bool intel_dp_mst_compute_config(
struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
struct intel_digital_port *intel_dig_port = intel_mst->primary;
struct intel_dp *intel_dp = &intel_dig_port->dp;
- struct intel_connector *connector =
- to_intel_connector(conn_state->connector);
+ struct drm_connector *connector = conn_state->connector;
+ void *port = to_intel_connector(connector)->port;
struct drm_atomic_state *state = pipe_config->base.state;
int bpp;
- int lane_count, slots;
+ int lane_count, slots = 0;
const struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
int mst_pbn;
bool reduce_m_n = drm_dp_has_quirk(&intel_dp->desc,
@@ -70,17 +70,23 @@ static bool intel_dp_mst_compute_config(

pipe_config->port_clock = intel_dp_max_link_rate(intel_dp);

- if (drm_dp_mst_port_has_audio(&intel_dp->mst_mgr, connector->port))
+ if (drm_dp_mst_port_has_audio(&intel_dp->mst_mgr, port))
pipe_config->has_audio = true;

mst_pbn = drm_dp_calc_pbn_mode(adjusted_mode->crtc_clock, bpp);
pipe_config->pbn = mst_pbn;

- slots = drm_dp_atomic_find_vcpi_slots(state, &intel_dp->mst_mgr,
- connector->port, mst_pbn);
- if (slots < 0) {
- DRM_DEBUG_KMS("failed finding vcpi slots:%d\n", slots);
- return false;
+ /* Zombie connectors can't have VCPI slots */
+ if (READ_ONCE(connector->registered)) {
+ slots = drm_dp_atomic_find_vcpi_slots(state,
+ &intel_dp->mst_mgr,
+ port,
+ mst_pbn);
+ if (slots < 0) {
+ DRM_DEBUG_KMS("failed finding vcpi slots:%d\n",
+ slots);
+ return false;
+ }
}

intel_link_compute_m_n(bpp, lane_count,