| Message ID | 20210208145821.517331268@linuxfoundation.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | None | expand |
Hi! > commit 83404d581471775f37f85e5261ec0d09407d8bed upstream. > > This function will be needed by the next patch where the driver > calculates the BW based on driver specific parameters, so export it. > > At the same time sanitize the function params, passing the more natural > link rate instead of the encoding of the same rate. > Cc: <stable@vger.kernel.org> This adds exports, but there's no user of the export, neither in 5.10-stable nor in linux-next. What is the plan here? Best regards, Pavel
Hi, On Wed, Feb 10, 2021 at 01:25:17PM +0100, Pavel Machek wrote: > Hi! > > > commit 83404d581471775f37f85e5261ec0d09407d8bed upstream. > > > > This function will be needed by the next patch where the driver > > calculates the BW based on driver specific parameters, so export it. > > > > At the same time sanitize the function params, passing the more natural > > link rate instead of the encoding of the same rate. > > > Cc: <stable@vger.kernel.org> > > This adds exports, but there's no user of the export, neither in > 5.10-stable nor in linux-next. What is the plan here? the export is used by the upstream commit 882554042d138dbc6fb1a43017d0b9c3b38ee5f5 Author: Imre Deak <imre.deak@intel.com> Date: Mon Jan 25 19:36:36 2021 +0200 drm/i915: Fix the MST PBN divider calculation which I can also see now applied to 5.10.15: commit 0fe98e455784a6c11e0dd48612acd343f4a46fce Author: Imre Deak <imre.deak@intel.com> AuthorDate: Mon Jan 25 19:36:36 2021 +0200 Commit: Greg Kroah-Hartman <gregkh@linuxfoundation.org> CommitDate: Wed Feb 10 09:29:18 2021 +0100 drm/i915: Fix the MST PBN divider calculation commit 882554042d138dbc6fb1a43017d0b9c3b38ee5f5 upstream. --Imre
--- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -3629,14 +3629,26 @@ static int drm_dp_send_up_ack_reply(stru return 0; } -static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8 dp_link_count) +/** + * drm_dp_get_vc_payload_bw - get the VC payload BW for an MST link + * @link_rate: link rate in 10kbits/s units + * @link_lane_count: lane count + * + * Calculate the total bandwidth of a MultiStream Transport link. The returned + * value is in units of PBNs/(timeslots/1 MTP). This value can be used to + * convert the number of PBNs required for a given stream to the number of + * timeslots this stream requires in each MTP. + */ +int drm_dp_get_vc_payload_bw(int link_rate, int link_lane_count) { - 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); + if (link_rate == 0 || link_lane_count == 0) + DRM_DEBUG_KMS("invalid link rate/lane count: (%d / %d)\n", + link_rate, link_lane_count); - return dp_link_bw * dp_link_count / 2; + /* See DP v2.0 2.6.4.2, VCPayload_Bandwidth_for_OneTimeSlotPer_MTP_Allocation */ + return link_rate * link_lane_count / 54000; } +EXPORT_SYMBOL(drm_dp_get_vc_payload_bw); /** * drm_dp_read_mst_cap() - check whether or not a sink supports MST @@ -3692,7 +3704,7 @@ int drm_dp_mst_topology_mgr_set_mst(stru goto out_unlock; } - mgr->pbn_div = drm_dp_get_vc_payload_bw(mgr->dpcd[1], + mgr->pbn_div = drm_dp_get_vc_payload_bw(drm_dp_bw_code_to_link_rate(mgr->dpcd[1]), mgr->dpcd[2] & DP_MAX_LANE_COUNT_MASK); if (mgr->pbn_div == 0) { ret = -EINVAL; --- a/include/drm/drm_dp_mst_helper.h +++ b/include/drm/drm_dp_mst_helper.h @@ -783,6 +783,7 @@ drm_dp_mst_detect_port(struct drm_connec struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port); +int drm_dp_get_vc_payload_bw(int link_rate, int link_lane_count); int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc);