[Intel-gfx] [PATCH 2/3] drm/dp/mst: Handle arbitrary DP_LINK_BW values

[Ville Syrjala]

From: Ville Syrjälä <ville.syrj...@linux.intel.com>

Make drm_dp_get_vc_payload() tolerate arbitrary DP_LINK_BW_*
values, just like drm_dp_bw_code_to_link_rate() does since commit
57a1b0893782 ("drm: Make the bw/link rate calculations more forgiving").

Cc: Lyude Paul <ly...@redhat.com>
Cc: Sean Paul <seanp...@chromium.org>
Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 29 ++++++---------------------
 1 file changed, 6 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c 
b/drivers/gpu/drm/drm_dp_mst_topology.c
index e25597eb3ca1..d4644a3c1324 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2974,30 +2974,13 @@ static int drm_dp_send_up_ack_reply(struct 
drm_dp_mst_topology_mgr *mgr,
        return 0;
 }
 
-static bool drm_dp_get_vc_payload_bw(int dp_link_bw,
-                                    int dp_link_count,
-                                    int *out)
+static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8  dp_link_count)
 {
-       switch (dp_link_bw) {
-       default:
+       if (dp_link_bw == 0 || dp_link_count == 0)
                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:
-               *out = 3 * dp_link_count;
-               break;
-       case DP_LINK_BW_2_7:
-               *out = 5 * dp_link_count;
-               break;
-       case DP_LINK_BW_5_4:
-               *out = 10 * dp_link_count;
-               break;
-       case DP_LINK_BW_8_1:
-               *out = 15 * dp_link_count;
-               break;
-       }
-       return true;
+       return dp_link_bw * dp_link_count / 2;
 }
 
 /**
@@ -3029,9 +3012,9 @@ int drm_dp_mst_topology_mgr_set_mst(struct 
drm_dp_mst_topology_mgr *mgr, bool ms
                        goto out_unlock;
                }
 
-               if (!drm_dp_get_vc_payload_bw(mgr->dpcd[1],
-                                             mgr->dpcd[2] & 
DP_MAX_LANE_COUNT_MASK,
-                                             &mgr->pbn_div)) {
+               mgr->pbn_div = drm_dp_get_vc_payload_bw(mgr->dpcd[1],
+                                                       mgr->dpcd[2] & 
DP_MAX_LANE_COUNT_MASK);
+               if (mgr->pbn_div == 0) {
                        ret = -EINVAL;
                        goto out_unlock;
                }
-- 
2.21.0

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