Messages in this thread |  | | Date | Wed, 1 Apr 2026 14:44:06 +0800 | | Subject | Re: [PATCH v3 17/38] drm/msm/dp: add support to send ACT packets for MST | | From | Yongxing Mou <> |
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On 8/26/2025 5:10 AM, Dmitry Baryshkov wrote: > On Mon, Aug 25, 2025 at 10:16:03PM +0800, Yongxing Mou wrote: >> From: Abhinav Kumar <quic_abhinavk@quicinc.com> >> >> Whenever virtual channel slot allocation changes, the DP >> source must send the action control trigger sequence to notify >> the sink about the same. This would be applicable during the >> start and stop of the pixel stream. Add the infrastructure >> to be able to send ACT packets for the DP controller when >> operating in MST mode. >> >> Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com> >> Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com> >> --- >> drivers/gpu/drm/msm/dp/dp_ctrl.c | 39 +++++++++++++++++++++++++++++++++++-- >> drivers/gpu/drm/msm/dp/dp_ctrl.h | 4 ++-- >> drivers/gpu/drm/msm/dp/dp_display.c | 3 ++- >> drivers/gpu/drm/msm/dp/dp_display.h | 1 + >> drivers/gpu/drm/msm/dp/dp_reg.h | 2 ++ >> 5 files changed, 44 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c >> index 608a1a077301b2ef3c77c271d873bb4364abe779..16e5ed58e791971d5dca3077cbb77bfcc186505a 100644 >> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c >> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c >> @@ -142,6 +142,7 @@ struct msm_dp_ctrl_private { >> bool core_clks_on; >> bool link_clks_on; >> bool stream_clks_on[DP_STREAM_MAX]; >> + bool mst_active; >> }; >> >> static inline u32 msm_dp_read_ahb(const struct msm_dp_ctrl_private *ctrl, u32 offset) >> @@ -227,6 +228,32 @@ static int msm_dp_aux_link_configure(struct drm_dp_aux *aux, >> return 0; >> } >> >> +void msm_dp_ctrl_mst_send_act(struct msm_dp_ctrl *msm_dp_ctrl) >> +{ >> + struct msm_dp_ctrl_private *ctrl; >> + bool act_complete; >> + >> + ctrl = container_of(msm_dp_ctrl, struct msm_dp_ctrl_private, msm_dp_ctrl); >> + >> + if (!ctrl->mst_active) >> + return; >> + >> + msm_dp_write_link(ctrl, REG_DP_MST_ACT, 0x1); >> + /* make sure ACT signal is performed */ >> + wmb(); >> + >> + msleep(20); /* needs 1 frame time */ >> + >> + act_complete = msm_dp_read_link(ctrl, REG_DP_MST_ACT); >> + >> + if (!act_complete) >> + drm_dbg_dp(ctrl->drm_dev, "mst ACT trigger complete SUCCESS\n"); >> + else >> + drm_dbg_dp(ctrl->drm_dev, "mst ACT trigger complete failed\n"); > > Shouldn't it return an error if the register dind't latch? Also, > shouldn't we set mst_active only if the write went through? > In some cases, MST still works correctly even when the ACT trigger fails; here refer to the downstream implementation. >> + >> + return; >> +} >> + >> /* >> * NOTE: resetting DP controller will also clear any pending HPD related interrupts >> */ >> @@ -2079,6 +2106,8 @@ static int msm_dp_ctrl_link_maintenance(struct msm_dp_ctrl_private *ctrl) >> >> msm_dp_write_link(ctrl, REG_DP_STATE_CTRL, DP_STATE_CTRL_SEND_VIDEO); >> >> + msm_dp_ctrl_mst_send_act(&ctrl->msm_dp_ctrl); >> + >> ret = msm_dp_ctrl_wait4video_ready(ctrl); >> end: >> return ret; >> @@ -2275,7 +2304,7 @@ static int msm_dp_ctrl_process_phy_test_request(struct msm_dp_ctrl_private *ctrl >> msm_dp_ctrl_off_pixel_clk(&ctrl->msm_dp_ctrl, ctrl->panel->stream_id); >> msm_dp_ctrl_off_link(&ctrl->msm_dp_ctrl); >> >> - ret = msm_dp_ctrl_on_link(&ctrl->msm_dp_ctrl); >> + ret = msm_dp_ctrl_on_link(&ctrl->msm_dp_ctrl, false); >> if (ret) { >> DRM_ERROR("failed to enable DP link controller\n"); >> return ret; >> @@ -2355,7 +2384,7 @@ static bool msm_dp_ctrl_channel_eq_ok(struct msm_dp_ctrl_private *ctrl) >> return drm_dp_channel_eq_ok(link_status, num_lanes); >> } >> >> -int msm_dp_ctrl_on_link(struct msm_dp_ctrl *msm_dp_ctrl) >> +int msm_dp_ctrl_on_link(struct msm_dp_ctrl *msm_dp_ctrl, bool mst_active) >> { >> int rc = 0; >> struct msm_dp_ctrl_private *ctrl; >> @@ -2373,6 +2402,7 @@ int msm_dp_ctrl_on_link(struct msm_dp_ctrl *msm_dp_ctrl) >> >> rate = ctrl->panel->link_info.rate; >> pixel_rate = ctrl->panel->msm_dp_mode.drm_mode.clock; >> + ctrl->mst_active = mst_active; >> >> msm_dp_ctrl_core_clk_enable(&ctrl->msm_dp_ctrl); >> >> @@ -2643,6 +2673,8 @@ int msm_dp_ctrl_on_stream(struct msm_dp_ctrl *msm_dp_ctrl, struct msm_dp_panel * >> >> msm_dp_write_link(ctrl, REG_DP_STATE_CTRL, DP_STATE_CTRL_SEND_VIDEO); >> >> + msm_dp_ctrl_mst_send_act(msm_dp_ctrl); >> + >> ret = msm_dp_ctrl_wait4video_ready(ctrl); >> if (ret) >> return ret; >> @@ -2682,6 +2714,8 @@ void msm_dp_ctrl_off_link(struct msm_dp_ctrl *msm_dp_ctrl) >> >> msm_dp_ctrl_reset(&ctrl->msm_dp_ctrl); >> >> + ctrl->mst_active = false; >> + >> dev_pm_opp_set_rate(ctrl->dev, 0); >> msm_dp_ctrl_link_clk_disable(&ctrl->msm_dp_ctrl); >> >> @@ -2849,6 +2883,7 @@ struct msm_dp_ctrl *msm_dp_ctrl_get(struct device *dev, struct msm_dp_link *link >> ctrl->link_base = link_base; >> ctrl->mst2link_base = mst2link_base; >> ctrl->mst3link_base = mst3link_base; >> + ctrl->mst_active = false; >> >> ret = msm_dp_ctrl_clk_init(&ctrl->msm_dp_ctrl, max_stream); >> if (ret) { >> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.h b/drivers/gpu/drm/msm/dp/dp_ctrl.h >> index 2baf7a1ff44dd7139d2da86390121d5e7a063e9a..abf84ddf463638900684f2511549a593783d2247 100644 >> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.h >> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.h >> @@ -16,7 +16,7 @@ struct msm_dp_ctrl { >> >> struct phy; >> >> -int msm_dp_ctrl_on_link(struct msm_dp_ctrl *msm_dp_ctrl); >> +int msm_dp_ctrl_on_link(struct msm_dp_ctrl *msm_dp_ctrl, bool mst_active); >> int msm_dp_ctrl_on_stream(struct msm_dp_ctrl *msm_dp_ctrl, struct msm_dp_panel *msm_dp_panel); >> int msm_dp_ctrl_prepare_stream_on(struct msm_dp_ctrl *msm_dp_ctrl, bool force_link_train); >> void msm_dp_ctrl_off_link(struct msm_dp_ctrl *msm_dp_ctrl); >> @@ -50,5 +50,5 @@ void msm_dp_ctrl_enable_irq(struct msm_dp_ctrl *msm_dp_ctrl); >> void msm_dp_ctrl_disable_irq(struct msm_dp_ctrl *msm_dp_ctrl); >> >> void msm_dp_ctrl_reinit_phy(struct msm_dp_ctrl *msm_dp_ctrl); >> - >> +void msm_dp_ctrl_mst_send_act(struct msm_dp_ctrl *msm_dp_ctrl); >> #endif /* _DP_CTRL_H_ */ >> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c >> index 562a5eccf3f08c5669cc7c2ad1268897e975d0c4..eeba73f81c5ce7929dac88f4b47ac3741659864b 100644 >> --- a/drivers/gpu/drm/msm/dp/dp_display.c >> +++ b/drivers/gpu/drm/msm/dp/dp_display.c >> @@ -709,7 +709,7 @@ static int msm_dp_display_prepare(struct msm_dp_display_private *dp) >> force_link_train = true; >> } >> >> - rc = msm_dp_ctrl_on_link(dp->ctrl); >> + rc = msm_dp_ctrl_on_link(dp->ctrl, msm_dp_display->mst_active); >> if (rc) { >> DRM_ERROR("Failed link training (rc=%d)\n", rc); >> msm_dp_display->connector->state->link_status = DRM_LINK_STATUS_BAD; >> @@ -1557,6 +1557,7 @@ void msm_dp_display_atomic_disable(struct msm_dp *dp) >> msm_dp_display = container_of(dp, struct msm_dp_display_private, msm_dp_display); >> >> msm_dp_ctrl_push_idle(msm_dp_display->ctrl); >> + msm_dp_ctrl_mst_send_act(msm_dp_display->ctrl); >> } >> >> static void msm_dp_display_unprepare(struct msm_dp_display_private *dp) >> diff --git a/drivers/gpu/drm/msm/dp/dp_display.h b/drivers/gpu/drm/msm/dp/dp_display.h >> index a839d0a3941eac3e277185e42fddea15ca05a17f..9442157bca9d63467b4c43fa644651ad2cbcbef5 100644 >> --- a/drivers/gpu/drm/msm/dp/dp_display.h >> +++ b/drivers/gpu/drm/msm/dp/dp_display.h >> @@ -21,6 +21,7 @@ struct msm_dp { >> bool audio_enabled; >> bool power_on; >> bool prepared; >> + bool mst_active; >> unsigned int connector_type; >> bool is_edp; >> bool internal_hpd; >> diff --git a/drivers/gpu/drm/msm/dp/dp_reg.h b/drivers/gpu/drm/msm/dp/dp_reg.h >> index a806d397ff9d9ad3830b1f539614bffcc955a786..de3d0b8b52c269fd7575edf3f4096a4284ad0b8d 100644 >> --- a/drivers/gpu/drm/msm/dp/dp_reg.h >> +++ b/drivers/gpu/drm/msm/dp/dp_reg.h >> @@ -158,6 +158,8 @@ >> #define DP_CONFIGURATION_CTRL_BPC_SHIFT (0x08) >> #define DP_CONFIGURATION_CTRL_LSCLK_DIV_SHIFT (0x0D) >> >> +#define REG_DP_MST_ACT (0x00000500) >> + >> #define REG_DP_SOFTWARE_MVID (0x00000010) >> #define REG_DP_SOFTWARE_NVID (0x00000018) >> #define REG_DP_TOTAL_HOR_VER (0x0000001C) >> >> -- >> 2.34.1 >> >
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