From 4b4659128e634ce65dc02acf297d623f5bc97497 Mon Sep 17 00:00:00 2001 From: Lyude Paul Date: Wed, 26 Aug 2020 14:24:45 -0400 Subject: drm/i915/dp: Extract drm_dp_read_mst_cap() Just a tiny drive-by cleanup, we can consolidate i915's code for checking for MST support into a helper to be shared across drivers. v5: * Drop !!() * Move drm_dp_has_mst() out of header * Change name from drm_dp_has_mst() to drm_dp_read_mst_cap() Signed-off-by: Lyude Paul Reviewed-by: Sean Paul Reviewed-by: Jani Nikula Link: https://patchwork.freedesktop.org/patch/msgid/20200826182456.322681-10-lyude@redhat.com --- drivers/gpu/drm/drm_dp_mst_topology.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'drivers/gpu/drm/drm_dp_mst_topology.c') diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index b23cb2fec3f3..61755c26fac0 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -3486,6 +3486,28 @@ static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8 dp_link_count) return dp_link_bw * dp_link_count / 2; } +/** + * drm_dp_read_mst_cap() - check whether or not a sink supports MST + * @aux: The DP AUX channel to use + * @dpcd: A cached copy of the DPCD capabilities for this sink + * + * Returns: %True if the sink supports MST, %false otherwise + */ +bool drm_dp_read_mst_cap(struct drm_dp_aux *aux, + const u8 dpcd[DP_RECEIVER_CAP_SIZE]) +{ + u8 mstm_cap; + + if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_12) + return false; + + if (drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &mstm_cap) != 1) + return false; + + return mstm_cap & DP_MST_CAP; +} +EXPORT_SYMBOL(drm_dp_read_mst_cap); + /** * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager * @mgr: manager to set state for -- cgit v1.2.3-70-g09d2