Re: [PATCH 0/5] drm/msm/dp: Add MSM Type-C MST support

[Yongxing Mou <yongxing.mou@oss.qualcomm.com>]

On 6/29/2026 10:48 PM, Yongxing Mou wrote:
> The bridge connector framework currently treats every HPD notification
> as a connector state update and emits a userspace hotplug event.
> Once MST is enabled, however, connector creation, removal and hotplug
> handling are already managed by the DRM DP MST topology manager.
> 
> As a result:
> 
>    - the SST connector may transiently transition between connected and
>      disconnected during MST initialization
> 
>    - MST IRQ notifications may generate duplicate userspace hotplug
>      events, once from the bridge connector layer and once from the MST
>      topology manager
> 
> Introduce explicit support for IRQ-only HPD notifications in the bridge
> connector framework and allow bridge drivers to suppress connector
> hotplug events when those events are already handled elsewhere.
> 
> MSM DP uses these mechanisms to integrate Type-C MST hubs without
> generating duplicate or spurious userspace hotplug notifications.
> 
> Testing
> -------
> Tested on Hamoa-EVK with a Type-C MST hub and dual-monitor setup.
> Both fbcon and Weston were exercised. No duplicate hotplug events,
> connector state oscillation or display flickering were observed after
> hub attachment.
> 
> Dependencies
> ------------
> This patch series was made on top of:
> 
> [1] drm: handle IRQ_HPD events correctly (v4)
>      https://lore.kernel.org/r/20260608-hpd-irq-events-v4-0-30b62b335487@oss.qualcomm.com
> 
Hi, Gentle ping on the IRQ HPD series. I'd like to understand whether 
the next version of this series is expected to separate the IRQ 
interfaces or continue with the current design.
> [2] drm/msm/dp: Add MST support for MSM chipsets (v5)
>      https://patchwork.freedesktop.org/series/142207/#rev5
> 
> [3] drm/msm/dp: Prerequisite cleanup for upcoming MST support (v7)
>      https://lore.kernel.org/r/20260609-dp_mstclean-v7-0-ea04113e8233@oss.qualcomm.com
> 
> Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
> ---
> Yongxing Mou (5):
>        drm/bridge: allow hpd_notify() to suppress connector hotplug events
>        drm/bridge_connector: preserve connector status for IRQ-only HPD events
>        drm/msm/dp: suppress bridge hotplug events during MST operation
>        drm/msm/dp: report IRQ_HPD as an IRQ-only notification
>        drm/msm/dp: mark the SST connector disconnected when MST is enabled
> 
>   drivers/gpu/drm/bridge/lontium-lt9611uxc.c     |  3 +-
>   drivers/gpu/drm/display/drm_bridge_connector.c | 31 ++++++++++++++++-----
>   drivers/gpu/drm/meson/meson_encoder_hdmi.c     |  3 +-
>   drivers/gpu/drm/msm/dp/dp_display.c            | 38 +++++++++++++++-----------
>   drivers/gpu/drm/msm/dp/dp_drm.h                |  3 +-
>   drivers/gpu/drm/omapdrm/dss/hdmi4.c            |  3 +-
>   drivers/soc/qcom/pmic_glink_altmode.c          | 14 ++++++----
>   include/drm/drm_bridge.h                       |  3 +-
>   8 files changed, 65 insertions(+), 33 deletions(-)
> ---
> base-commit: e7d700e14934e68f86338c5610cf2ae76798b663
> change-id: 20260629-msm-dp-msttypec-b420df7da587
> prerequisite-message-id: <20260608-hpd-irq-events-v4-0-30b62b335487@oss.qualcomm.com>
> prerequisite-patch-id: adc6d802a2f71d23c077a5cdb9a257809e9db50e
> prerequisite-patch-id: bbd956a3b65a90c1fe9e884bc32c49bd83fd3129
> prerequisite-patch-id: 014460a25c380d089764ab4e1a58577ebc1b9e71
> prerequisite-patch-id: fc03fb9435b8c60321f9ae28e396a6bff2f347ae
> prerequisite-patch-id: cd4cd57a72c798fc95afdfdeb9b81cc7a2dbd25d
> prerequisite-patch-id: fe431fb614383eb6444f6bfb928e7e40c2de951e
> prerequisite-patch-id: 2a058aa8309016f424b1d4ca19a9b20e92f4d8b6
> prerequisite-patch-id: 64c3616bb979b663a01342d1f217588b347ae8bb
> prerequisite-change-id: 20260410-msm-dp-mst-35130b6e8b84:v5
> prerequisite-patch-id: 1d440cb9fed2bdd66d8de0e1e20475f0fe166973
> prerequisite-patch-id: be0f4b80697df7224c80362b161b8a9f0a542184
> prerequisite-patch-id: eefa6e6353df301420feae1da704a9db2c2155f2
> prerequisite-patch-id: 9e9095f82dd6c131c9f3c1de4fdb8a62bd65ca24
> prerequisite-patch-id: 3e635f008f9b56823101abd9253905f078fcb3b5
> prerequisite-patch-id: e39e0dc124ed043c7a419610ebe03ad105da27db
> prerequisite-patch-id: 945af39213cd4241e1a5929fada04a9286aeb5db
> prerequisite-patch-id: 898ae7e4582a6b31492c223e7dd167fb9ce78096
> prerequisite-patch-id: 3887553893357c1ffbda99eb010801bc2166cbad
> prerequisite-patch-id: 7ccd961fa3c6f925659dee7d7a5bd167c8e7331b
> prerequisite-patch-id: be2bf918e0e87ec2ea999927f36bd172c498748e
> prerequisite-patch-id: 6aacdabb2dd0536dc04da04f8419ae39e35f8b19
> prerequisite-patch-id: a9f27eff8f643ff445810b17d670891928f5b416
> prerequisite-patch-id: efd300a2b52715153b8c1c7407db696eb331594b
> prerequisite-patch-id: 950abefc4862050ef606404977fd27c5dd2cbb2b
> prerequisite-patch-id: c6a9aaba753b5538864f7f6e065d910833baec21
> prerequisite-patch-id: c73c1f6eb16b2a6ff11b20495fa0981683bdaaee
> prerequisite-patch-id: 94957394b3870ec63ab766d682df592da978dd19
> prerequisite-patch-id: f27cba0cf5f08d21f59f29a0c9ed7f197ddfa2c7
> prerequisite-patch-id: 683855949a9ed37bc0cc4d1899373e55eac4ddc3
> prerequisite-patch-id: 9b3a2b526476c32c8a859824e551e23412674766
> prerequisite-patch-id: be866cf2acd4960f31f0dbd05e21f0722dcb70ab
> prerequisite-patch-id: 58bd115be590c0d892a72e06794f5b244dbdb7f8
> prerequisite-patch-id: 87435a0f6827516f4e2b5d8471a2b289bb73a88c
> prerequisite-patch-id: 1064db7111fc77377dbf246eb0fdef90c18c46ee
> prerequisite-patch-id: e112aaf6088f2bfa90bc67feaac86a4fc1ad23ca
> prerequisite-patch-id: fcc0f2ee6dc0358d62593c1295d26a013fa11223
> prerequisite-patch-id: 66364b8806fc6abeabe1a0b871e4e8c841ce2aa7
> prerequisite-patch-id: 243046f52a14b416caead3469d580ea5b029f9bb
> prerequisite-patch-id: efd8014f647a6aa5fadc9d62a6e1920d76a6c80f
> prerequisite-patch-id: f4dbd5ae84a01ea89c7d00ca39fd76cd247bc353
> prerequisite-patch-id: 30a16a45edefc8769b10d90a7807b6522cd31f15
> prerequisite-patch-id: e12fd2908ca33de1f1265fd40190eaad8637e569
> prerequisite-patch-id: 3baac076fdda664d00aa9a83481f76ec38c07e8a
> prerequisite-patch-id: ee6a93ffa2d5461ee7b07929ff21626a14773b7a
> prerequisite-patch-id: c8d444e2a6512f106da2675d4a42a92208d5c6f1
> prerequisite-patch-id: 0491a69feb036cfa2e75401e093ebad387cf2846
> prerequisite-patch-id: 707e7a3e5114c86f5bcc0b36e7cc8beb0c957780
> prerequisite-patch-id: b1ae90d73bd7c3d19cfe4371b5dc9a816f1316a6
> prerequisite-patch-id: 4c183b8ffd599169c8d3c5f3aad5ecc467b150f2
> prerequisite-message-id: <20260609-dp_mstclean-v7-0-ea04113e8233@oss.qualcomm.com>
> prerequisite-patch-id: 1d440cb9fed2bdd66d8de0e1e20475f0fe166973
> prerequisite-patch-id: be0f4b80697df7224c80362b161b8a9f0a542184
> prerequisite-patch-id: eefa6e6353df301420feae1da704a9db2c2155f2
> prerequisite-patch-id: 9e9095f82dd6c131c9f3c1de4fdb8a62bd65ca24
> prerequisite-patch-id: 3e635f008f9b56823101abd9253905f078fcb3b5
> prerequisite-patch-id: e39e0dc124ed043c7a419610ebe03ad105da27db
> prerequisite-patch-id: 945af39213cd4241e1a5929fada04a9286aeb5db
> prerequisite-patch-id: 898ae7e4582a6b31492c223e7dd167fb9ce78096
> prerequisite-patch-id: 3887553893357c1ffbda99eb010801bc2166cbad
> prerequisite-patch-id: 7ccd961fa3c6f925659dee7d7a5bd167c8e7331b
> prerequisite-patch-id: be2bf918e0e87ec2ea999927f36bd172c498748e
> prerequisite-patch-id: 6aacdabb2dd0536dc04da04f8419ae39e35f8b19
> prerequisite-patch-id: a9f27eff8f643ff445810b17d670891928f5b416
> prerequisite-patch-id: efd300a2b52715153b8c1c7407db696eb331594b
> prerequisite-patch-id: 950abefc4862050ef606404977fd27c5dd2cbb2b
> 
> Best regards,