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[129.46.232.65]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8ac84cb135fsm19223386d6.38.2026.04.10.02.36.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Apr 2026 02:36:17 -0700 (PDT) From: Yongxing Mou Date: Fri, 10 Apr 2026 17:34:04 +0800 Subject: [PATCH v4 29/39] drm/msm/dp: add an API to initialize MST on sink side Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260410-msm-dp-mst-v4-29-b20518dea8de@oss.qualcomm.com> References: <20260410-msm-dp-mst-v4-0-b20518dea8de@oss.qualcomm.com> In-Reply-To: <20260410-msm-dp-mst-v4-0-b20518dea8de@oss.qualcomm.com> To: Rob Clark , Dmitry Baryshkov , Abhinav Kumar , Sean Paul , Marijn Suijten , David Airlie , Simona Vetter , Jessica Zhang Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org, Yongxing Mou , Abhinav Kumar X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1775813628; l=3422; i=yongxing.mou@oss.qualcomm.com; s=20250910; h=from:subject:message-id; bh=0Fikc4rnY1UekND7dRzqfk9ihtHHa+1WVLOx8xNYQ4o=; b=8hLy4E3IvJa2/IITkmxuQf2Wv5ngHhhb4QUgFjbsYdAiYbRSJwQd5KzIEu7dyeYgwGFmLpyc9 HSXKtsPBq4vCeEwjzSFU4cgwzG5Fc6sYOnSxY1LINd1pZBOCqp2I7U9 X-Developer-Key: i=yongxing.mou@oss.qualcomm.com; a=ed25519; pk=rAy5J1eP+V7OXqH5FJ7ngMCtUrnHhut30ZTldOj52UM= X-Authority-Analysis: v=2.4 cv=PMM/P/qC c=1 sm=1 tr=0 ts=69d8c493 cx=c_pps a=oc9J++0uMp73DTRD5QyR2A==:117 a=C3Dk8TwHQYyIj7nOf9RCJw==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=YMgV9FUhrdKAYTUUvYB2:22 a=COk6AnOGAAAA:8 a=EUspDBNiAAAA:8 a=vCCEq3Mv4WXTdc8uXsoA:9 a=QEXdDO2ut3YA:10 a=iYH6xdkBrDN1Jqds4HTS:22 a=TjNXssC_j7lpFel5tvFf:22 X-Proofpoint-ORIG-GUID: nii43wET4sO0M1LcXV5zZb1DFUX8yHym X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDEwMDA4OSBTYWx0ZWRfX0DEO561UtGYQ HEu2c8CE4z6gOogrxXhYV9Q2XOX4gUcRICprWr/faiu5LodqDz63q1i8CR+GwhHHP3jNIxAseJc +nU0Q62wvZL/FttP1BzDeDAXbIuzO768LjcJsGMNAJqxehvDrMIcu0Hw4uyV6RkMPIwkSlJ0uxZ N1gaTPDCLCNBOUnbw95iG+vClO3+L2nasK5WxFPORvUWP2vcbiODwZ3vnC/yKoBCxoyTOZiw0zz eLelSDtUH0g5hFVTXdqUdeSKl1WisF/BzdHO8zWgm69HBlqOxesRCKWOr/nnn7FPQIWAa4JNlHJ Gy2Ijb8GcAGZL5ufJaiNUsytW5GxraWp0ip+7iErxsdHKDOZsn/Eu9sKgE3sUDE9bsdvfMaxeCv uuczKp/E16UoSJAMVpx8e/hiMKNAD2FZP1Q/YAtFRhIX4Aog7KktkTNyQBdW+jpGOCYvKHZd53w nJpIPAA6IyrtpWDAAnw== X-Proofpoint-GUID: nii43wET4sO0M1LcXV5zZb1DFUX8yHym X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-10_03,2026-04-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 priorityscore=1501 adultscore=0 lowpriorityscore=0 bulkscore=0 phishscore=0 clxscore=1015 malwarescore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604010000 definitions=main-2604100089 From: Abhinav Kumar If the DP controller is capable of supporting multiple streams then initialize the DP sink in MST mode by programming the DP_MSTM_CTRL DPCD register to enable MST mode. Signed-off-by: Abhinav Kumar Signed-off-by: Yongxing Mou --- drivers/gpu/drm/msm/dp/dp_display.c | 57 ++++++++++++++++++++++++++++++++----- 1 file changed, 50 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c index 8ae690ce2b9f..abf26951819a 100644 --- a/drivers/gpu/drm/msm/dp/dp_display.c +++ b/drivers/gpu/drm/msm/dp/dp_display.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include "msm_drv.h" @@ -270,6 +271,40 @@ static int msm_dp_display_lttpr_init(struct msm_dp_display_private *dp, u8 *dpcd return lttpr_count; } +static void msm_dp_display_mst_init(struct msm_dp_display_private *dp) +{ + const unsigned long clear_mstm_ctrl_timeout_us = 100000; + u8 old_mstm_ctrl; + struct msm_dp *msm_dp = &dp->msm_dp_display; + int ret; + + /* clear sink MST state */ + drm_dp_dpcd_read_byte(dp->aux, DP_MSTM_CTRL, &old_mstm_ctrl); + + ret = drm_dp_dpcd_write_byte(dp->aux, DP_MSTM_CTRL, 0); + if (ret < 0) { + DRM_ERROR("failed to clear DP_MSTM_CTRL, ret=%d\n", ret); + return; + } + + /* add extra delay if MST old state is on*/ + if (old_mstm_ctrl) { + drm_dbg_dp(dp->drm_dev, "wait %luus to set DP_MSTM_CTRL set 0\n", + clear_mstm_ctrl_timeout_us); + usleep_range(clear_mstm_ctrl_timeout_us, + clear_mstm_ctrl_timeout_us + 1000); + } + + ret = drm_dp_dpcd_write_byte(dp->aux, DP_MSTM_CTRL, + DP_MST_EN | DP_UP_REQ_EN | DP_UPSTREAM_IS_SRC); + if (ret < 0) { + DRM_ERROR("sink MST enablement failed\n"); + return; + } + + msm_dp->mst_active = true; +} + static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp) { struct drm_connector *connector = dp->msm_dp_display.connector; @@ -288,14 +323,19 @@ static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp) if (rc) goto end; - drm_edid = drm_edid_read_ddc(connector, &dp->aux->ddc); - drm_edid_connector_update(connector, drm_edid); + if (!(dp->max_stream > 1) || !drm_dp_read_mst_cap(dp->aux, dp->panel->dpcd)) { + drm_edid = drm_edid_read_ddc(connector, &dp->aux->ddc); + drm_edid_connector_update(connector, drm_edid); - if (!drm_edid) { - DRM_ERROR("panel edid read failed\n"); - /* check edid read fail is due to unplug */ - if (!msm_dp_aux_is_link_connected(dp->aux)) - return -ETIMEDOUT; + if (!drm_edid) { + DRM_ERROR("panel edid read failed\n"); + /* check edid read fail is due to unplug */ + if (!msm_dp_aux_is_link_connected(dp->aux)) + return -ETIMEDOUT; + } + + if (rc) + goto end; } msm_dp_link_process_request(dp->link); @@ -317,6 +357,9 @@ static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp) */ msm_dp_link_psm_config(dp->link, &dp->panel->link_info, false); + if (dp->max_stream > 1 && drm_dp_read_mst_cap(dp->aux, dp->panel->dpcd)) + msm_dp_display_mst_init(dp); + msm_dp_link_reset_phy_params_vx_px(dp->link); end: -- 2.43.0