[Intel-gfx] [PATCH 2/4] drm/i915: Fix intel_dp_mst_compute_link_config

Stanislav Lisovskiy
2022-08-29T09:58:07Z

We currently always exit that bpp loop because drm_dp_atomic_find_vcpi_slots
doesn't care if we actually can fit those or not.
I think that wasn't the initial intention here, especially when
we keep trying with lower bpps, we are supposed to keep trying
until we actually find some _working_ configuration, which isn't the
case here.
So added that drm_dp_mst_check here, so that we can make sure
that try all the bpps before we fail.

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
---
drivers/gpu/drm/i915/display/intel_dp_mst.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 13abe2b2170e..c4f92edbdd08 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -60,6 +60,7 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
&crtc_state->hw.adjusted_mode;
bool constant_n = drm_dp_has_quirk(&intel_dp->desc, DP_DPCD_QUIRK_CONSTANT_N);
int bpp, slots = -EINVAL;
+ int ret = 0;

mst_state = drm_atomic_get_mst_topology_state(state, &intel_dp->mst_mgr);
if (IS_ERR(mst_state))
@@ -85,10 +86,21 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
connector->port, crtc_state->pbn);
if (slots == -EDEADLK)
return slots;
- if (slots >= 0)
- break;
+ if (slots >= 0) {
+ ret = drm_dp_mst_atomic_check(state);
+ /*
+ * If we got slots >= 0 and we can fit those based on check
+ * then we can exit the loop. Otherwise keep trying.
+ */
+ if (!ret)
+ break;
+ }
}

+ /* Despite slots are non-zero, we still failed the atomic check */
+ if (ret && slots >= 0)
+ slots = ret;
+
if (slots < 0) {
drm_dbg_kms(&i915->drm, "failed finding vcpi slots:%d\n",
slots);
--
2.24.1.485.gad05a3d8e5