Reviewed-by: Vinod Govindapillai <vinod.govindapillai@xxxxxxxxx>
On Mon, 2022-08-29 at 12:58 +0300, Stanislav Lisovskiy wrote:
> 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@xxxxxxxxx>
> ---
> 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);
