Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b853fdb3 authored by Chris Wilson's avatar Chris Wilson Committed by Dave Airlie
Browse files

drm/dp/mst: Handle invalid link bandwidth from DPCD gracefully 

Don't BUG out if the link reports an invalid (or plain unknown)
bandwidth value, but report the failure and fail gracefully.

Fixes a trivial compiler warning in case the BUG is ever compiled away.

Link: http://lkml.kernel.org/p/1415785566-12758-1-git-send-email-geert@linux-m68k.org


Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent db883628

drivers/gpu/drm/drm_dp_mst_topology.c

+22 −6
Original line number Diff line number Diff line
@@ -1799,17 +1799,27 @@ static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr, 
	return 0;

}



static int drm_dp_get_vc_payload_bw(int dp_link_bw, int dp_link_count)

static bool drm_dp_get_vc_payload_bw(int dp_link_bw,

				     int dp_link_count,

				     int *out)

{

	switch (dp_link_bw) {

	default:

		DRM_DEBUG_KMS("invalid link bandwidth in DPCD: %x (link count: %d)\n",

			      dp_link_bw, dp_link_count);

		return false;



	case DP_LINK_BW_1_62:

		return 3 * dp_link_count;

		*out = 3 * dp_link_count;

		break;

	case DP_LINK_BW_2_7:

		return 5 * dp_link_count;

		*out = 5 * dp_link_count;

		break;

	case DP_LINK_BW_5_4:

		return 10 * dp_link_count;

		*out = 10 * dp_link_count;

		break;

	}

	BUG();

	return true;

}



/**
@@ -1841,7 +1851,13 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms 
			goto out_unlock;

		}



		mgr->pbn_div = drm_dp_get_vc_payload_bw(mgr->dpcd[1], mgr->dpcd[2] & DP_MAX_LANE_COUNT_MASK);

		if (!drm_dp_get_vc_payload_bw(mgr->dpcd[1],

					      mgr->dpcd[2] & DP_MAX_LANE_COUNT_MASK,

					      &mgr->pbn_div)) {

			ret = -EINVAL;

			goto out_unlock;

		}



		mgr->total_pbn = 2560;

		mgr->total_slots = DIV_ROUND_UP(mgr->total_pbn, mgr->pbn_div);

		mgr->avail_slots = mgr->total_slots;