Re: [PATCH 2/3] drm/dp/mst: Handle arbitrary DP_LINK_BW values

Reviewed-by: Lyude Paul lyude@redhat.com

On Wed, 2019-09-25 at 17:14 +0300, Ville Syrjala wrote:

From: Ville Syrjälä ville.syrjala@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 lyude@redhat.com Cc: Sean Paul seanpaul@chromium.org Signed-off-by: Ville Syrjälä ville.syrjala@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;
  

  }