Re: [PATCH v2 00/38] drm/msm/dp: Add MST support for MSM chipsets

[Yongxing Mou]

On 2025/6/10 16:30, Dmitry Baryshkov wrote:
> On Tue, Jun 10, 2025 at 12:47:00PM +0800, Yongxing Mou wrote:
> > On 2025/6/9 20:36, Dmitry Baryshkov wrote:
> > > On Mon, Jun 09, 2025 at 08:21:19PM +0800, Yongxing Mou wrote:
> > > > Add support for Multi-stream transport for MSM chipsets that allow
> > > > a single instance of DP controller to send multiple streams.
> > > >
> > > > This series has been validated on sa8775p ride platform using multiple
> > > > MST dongles and also daisy chain method on both DP0 and DP1 upto 1080P.
> > >
> > > Which means that you didn't validate the MST interaction with the USB-C
> > > stack (there is a significant difference in the way HPD event is handled
> > > in the Linux kernel).
> > Yes. this patch series not test with USB-DP. Actually, our initial plan was
> > 2x2 MST on SA8775P and 4 MST on ACS8300. All of them are native DP
> > interface, not USB-DP. So can we only support SA8775P/QCS8300 in this
> > series. We don't plan to support other platform in this patch series.
>
> I'm sorry, it doesn't work this way. This is not a product kernel,
> limited to a selected set of platforms. So, you have to hook MST support
> in both paths. The series is not going to be merged tomorrow, so you
> have enough time to validate MST on the platforms providing DP over
> USB-C.
Would it be okay to implement USB-C DP MST in a separate patch series later?
> > > > With 4x4K monitors, due to lack of layer mixers that combination will not
> > > > work but this can be supported as well after some rework on the DPU side.
> > > >
> > > > In addition, SST was re-validated with all these changes to ensure there
> > > > were no regressions.
> > > >
> > > > This patch series was made on top of:
> > > >
> > > > [1] : https://patchwork.freedesktop.org/seriedds/142010/ (v2 to fix up HPD)
> > >
> > > This series has serious concerns and most likely will not be merged. Not
> > > to mention that the URL is invalid.
> > Got it. Sorry for the typo in the URL. So should we drop this patch series
> > or wait the state machine rework from Jessica zhang ?
>
> Please work with Jessica. As I wrote, I do not intend to land the
> mentioned series.
>
> > > > Bindings for the pixel clock for additional stream is available at :
> > > >
> > > > [2] : https://patchwork.freedesktop.org/series/142016/
> > >
> > > This series needs another revision.
> > Got it.
> > > Not to mention that I plan to land [3] this cycle
> > >
> > > [3] http://lore.kernel.org/dri-devel/20250518-fd-dp-audio-fixup-v6-0-2f0ec3ec000d@xxxxxxxxxxxxxxxx
> > Got it. will rebase on this patch series.
> > > > Overall, the patch series has been organized in the following way:
> > > >
> > > > 1) First set are a couple of fixes made while debugging MST but applicable
> > > > to SST as well so go ahead of everything else
> > > > 2) Prepare the DP driver to get ready to handle multiple streams. This is the bulk
> > > > of the work as current DP driver design had to be adjusted to make this happen.
> > > > 3) Finally, new files to handle MST related operations
> > > >
> > > > Validation was done on the latest linux-next on top of above changes and
> > > > both FB console and weston compositors were validated with these changes.
> > >
> > > Validation should be using IGT for testing. Please ensure that there are
> > > no regressions.
> > >
> > > > To: Rob Clark <robin.clark@xxxxxxxxxxxxxxxx>
> > > > To: Dmitry Baryshkov <lumag@xxxxxxxxxx>
> > > > To: Abhinav Kumar <abhinav.kumar@xxxxxxxxx>
> > > > To: Jessica Zhang <jessica.zhang@xxxxxxxxxxxxxxxx>
> > > > To: Sean Paul <sean@xxxxxxxxxx>
> > > > To: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx>
> > > > To: David Airlie <airlied@xxxxxxxxx>
> > > > To: Simona Vetter <simona@xxxxxxxx>
> > > > Cc: linux-arm-msm@xxxxxxxxxxxxxxx
> > > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > > > Cc: freedreno@xxxxxxxxxxxxxxxxxxxxx
> > > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > > >
> > > > Signed-off-by: Yongxing Mou <quic_yongmou@xxxxxxxxxxx>
> > > > ---
> > > > Changes in v2: Fixed review comments from Dmitry
> > > > - Rebase on top of next-20250606
> > > > - Add all 4 streams pixel clks support and MST2/MST3 Link clk support
> > > > - Address the formatting issues mentioned in the review comments
> > > > - Drop the cache of msm_dp_panel->drm_edid cached
> > > > - Remove the one-line wrapper funtion and redundant conditional check
> > > > - Fixed the commit messgae descriptions of some patches
> > > > - Reordered the patches and renamed some functions and variables
> > > > - Link to v1: https://lore.kernel.org/all/20241205-dp_mst-v1-0-f
> > > > 8618d42a99a@xxxxxxxxxxx/
> > > >
> > > > ---
> > > > Abhinav Kumar (35):
> > > >         drm/msm/dp: split msm_dp_panel_read_sink_caps() into two parts and drop panel drm_edid
> > > >         drm/msm/dp: remove dp_display's dp_mode and use dp_panel's instead
> > > >         drm/msm/dp: break up dp_display_enable into two parts
> > > >         drm/msm/dp: re-arrange dp_display_disable() into functional parts
> > > >         drm/msm/dp: allow dp_ctrl stream APIs to use any panel passed to it
> > > >         drm/msm/dp: move the pixel clock control to its own API
> > > >         drm/msm/dp: split dp_ctrl_off() into stream and link parts
> > > >         drm/msm/dp: make bridge helpers use dp_display to allow re-use
> > > >         drm/msm/dp: separate dp_display_prepare() into its own API
> > > >         drm/msm/dp: introduce the max_streams for dp controller
> > > >         drm/msm/dp: introduce stream_id for each DP panel
> > > >         drm/msm/dp: add support for programming p1/p2/p3 register block
> > > >         drm/msm/dp: use stream_id to change offsets in dp_catalog
> > > >         drm/msm/dp: add support to send ACT packets for MST
> > > >         drm/msm/dp: add support to program mst support in mainlink
> > > >         drm/msm/dp: no need to update tu calculation for mst
> > > >         drm/msm/dp: add support for mst channel slot allocation
> > > >         drm/msm/dp: add support to send vcpf packets in dp controller
> > > >         drm/msm/dp: always program MST_FIFO_CONSTANT_FILL for MST
> > > >         drm/msm/dp: abstract out the dp_display stream helpers to accept a panel
> > > >         drm/msm/dp: move link related operations to dp_display_unprepare()
> > > >         drm/msm/dp: replace power_on with active_stream_cnt for dp_display
> > > >         drm/msm/dp: make the SST bridge disconnected when mst is active
> > > >         drm/msm/dp: add an API to initialize MST on sink side
> > > >         drm/msm/dp: skip reading the EDID for MST cases
> > > >         drm/msm/dp: add dp_display_get_panel() to initialize DP panel
> > > >         drm/msm/dp: add dp_mst_drm to manage DP MST bridge operations
> > > >         drm/msm/dp: add connector abstraction for DP MST
> > > >         drm/msm/dp: add HPD callback for dp MST
> > > >         drm/msm: add support for non-blocking commits
> > > >         drm/msm: initialize DRM MST encoders for DP controllers
> > > >         drm/msm/dp: initialize dp_mst module for each DP MST controller
> > > >         drm/msm/dpu: use msm_dp_get_mst_intf_id() to get the intf id
> > > >         drm/msm/dp: mark ST_DISCONNECTED only if all streams are disabled
> > > >         drm/msm/dp: fix the intf_type of MST interfaces
> > > >
> > > > Yongxing Mou (3):
> > > >         drm/msm/dp: Add catalog support for 3rd/4th stream MST
> > > >         drm/msm/dp: propagate MST state changes to dp mst module
> > > >         drm/msm/dp: Add MST stream support for SA8775P DP controller 0 and 1
> > > >
> > > >    drivers/gpu/drm/msm/Makefile                       |    3 +-
> > > >    .../drm/msm/disp/dpu1/catalog/dpu_8_4_sa8775p.h    |    8 +-
> > > >    drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c        |   21 +-
> > > >    drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h        |    2 +
> > > >    drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c            |   72 +-
> > > >    drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h            |    2 +-
> > > >    drivers/gpu/drm/msm/dp/dp_audio.c                  |    2 +-
> > > >    drivers/gpu/drm/msm/dp/dp_catalog.c                |  558 ++++++++--
> > > >    drivers/gpu/drm/msm/dp/dp_catalog.h                |   64 +-
> > > >    drivers/gpu/drm/msm/dp/dp_ctrl.c                   |  474 ++++++---
> > > >    drivers/gpu/drm/msm/dp/dp_ctrl.h                   |   22 +-
> > > >    drivers/gpu/drm/msm/dp/dp_display.c                |  510 +++++++---
> > > >    drivers/gpu/drm/msm/dp/dp_display.h                |   33 +-
> > > >    drivers/gpu/drm/msm/dp/dp_drm.c                    |   53 +-
> > > >    drivers/gpu/drm/msm/dp/dp_drm.h                    |   12 -
> > > >    drivers/gpu/drm/msm/dp/dp_mst_drm.c                | 1065 ++++++++++++++++++++
> > > >    drivers/gpu/drm/msm/dp/dp_mst_drm.h                |  106 ++
> > > >    drivers/gpu/drm/msm/dp/dp_panel.c                  |   66 +-
> > > >    drivers/gpu/drm/msm/dp/dp_panel.h                  |   10 +-
> > > >    drivers/gpu/drm/msm/dp/dp_reg.h                    |   46 +-
> > > >    drivers/gpu/drm/msm/msm_atomic.c                   |    3 +
> > > >    drivers/gpu/drm/msm/msm_drv.h                      |   19 +
> > > >    drivers/gpu/drm/msm/msm_kms.c                      |    2 +
> > > >    23 files changed, 2725 insertions(+), 428 deletions(-)
> > > > ---
> > > > base-commit: 475c850a7fdd0915b856173186d5922899d65686
> > > > change-id: 20250609-msm-dp-mst-cddc2f61daee
> > > > prerequisite-message-id: <20250529-hpd_display_off-v1-0-ce33bac2987c@xxxxxxxxxxxxxxxx>
> > > > prerequisite-patch-id: a1f426b99b4a99d63daa9902cde9ee38ae1128d1
> > > > prerequisite-patch-id: ae9e0a0db8edd05da06f9673e9de56761654ed3c
> > > > prerequisite-patch-id: 7cb84491c6c3cf73480343218c543d090f8cb5e2
> > > > prerequisite-patch-id: f32638e79dd498db2075735392e85729b1b691fc
> > > > prerequisite-message-id: <20250530-dp_mst_bindings-v2-0-f925464d32a8@xxxxxxxxxxxxxxxx>
> > > > prerequisite-patch-id: e505c21f653c8e18ce83cad1fc787c13a6c8ed12
> > > > prerequisite-patch-id: cfdd5c37d38b2a4f1386af4021ba3920c6d8dcf8
> > > > prerequisite-patch-id: f4abdddcb90c8203044395f4768d794214fe3225
> > > > prerequisite-patch-id: 45013dfaf34856422b7b6b3d2ee42d81a917177b
> > > > prerequisite-patch-id: 2f35bedb0410bead1b66cbfaf51984fc7016828f
> > > >
> > > > Best regards,
> > > > --
> > > > Yongxing Mou <quic_yongmou@xxxxxxxxxxx>