We just added a new helper for DPCD retrieval to drm_dp_helper.c (which also handles grabbing the extended receiver caps), we should probably make use of it here
On Wed, 2020-09-09 at 14:31 +0800, Koba Ko wrote:
On Thu, Aug 27, 2020 at 1:30 PM Koba Ko koba.ko@canonical.com wrote:
Currently, DRM get the capability of the mst hub only from DP_DPCD_REV and get the slower speed even the mst hub can run in the faster speed.
As per DP-1.3, First check DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT. If DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT is 1, read the DP_DP13_DPCD_REV to get the faster capability. If DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT is 0, read DP_DPCD_REV.
Signed-off-by: Koba Ko koba.ko@canonical.com
drivers/gpu/drm/drm_dp_mst_topology.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 67dd72ea200e..3b84c6801281 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -3497,6 +3497,8 @@ static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8 dp_link_count) int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state) { int ret = 0;
u8 dpcd_ext = 0;unsigned int dpcd_offset = 0; struct drm_dp_mst_branch *mstb = NULL; mutex_lock(&mgr->payload_lock);@@ -3510,9 +3512,15 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms struct drm_dp_payload reset_pay;
WARN_ON(mgr->mst_primary);
drm_dp_dpcd_read(mgr->aux,DP_TRAINING_AUX_RD_INTERVAL,&dpcd_ext, sizeof(dpcd_ext));dpcd_offset =((dpcd_ext &DP_EXTENDED_RECEIVER_CAP_FIELD_PRESENT) ? DP_DP13_DPCD_REV : DP_DPCD_REV);
/* get dpcd info */
ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd,DP_RECEIVER_CAP_SIZE);
ret = drm_dp_dpcd_read(mgr->aux, dpcd_offset, mgr->dpcd,DP_RECEIVER_CAP_SIZE); if (ret != DP_RECEIVER_CAP_SIZE) { DRM_DEBUG_KMS("failed to read DPCD\n"); goto out_unlock; -- 2.25.1
Add Lyude Paul