Re: [PATCH v7 00/14] Add support for Common SDP Transmission Line

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 9/15/2026 10:16 PM, Ankit Nautiyal wrote:
> Xe3p_lpd introduces new register bits to program a common SDP
> Transmission line that will be used by the Hardware to position the
> SDPs. Along with this, another new register is also added to stagger
> the different SDPs.
>
> This series adds support for programming the Common SDP Transmission Line
> (CMN_SDP_TL) and its stagger control registers.
>
> Rev2:
>   - Add tracking for AS SDP Transmission line first. Instead of directly
>     programming it in the register, compute the state during
>     compute_config_late() and write the value from crtc_state.
>     Readout from the register through a vrr helper, since the register is
>     defined in context of VRR and will be used for both DP and HDMI VRR
>     packets.
>   - Add support to track other SDP transmission lines, instead of stagger
>     values.
>   - Compute the transmission lines in compute_config_late path and add
>     readout.
>   - Always write the Common SDP Transmission line and other stagger
>     values, whether the packets are sent or not.
>   - Dump SDP transmission lines in crtc_state.
>
> Rev3:
>   - Introduce new files for handling the Data Island Packets (DIPs)
>     programming in one place. (Ville)
>   - Extract the Transmission Line programming for
>     HDMI Extended Metadata Packet (EMP) and Adaptive Sync SDP (AS SDP)
>     i.e. EMP_AS_SDP_TL in the new file.
>   - Add programming for Common Base SDP Transmission lines and other
>     stagger offsets in the new file.
>   - Add a #TODO to extract other helpers that deal with Data Island Packets
>     and VIDEO_DIP registers.
>   - Place the HAS_* Macros related to DIP in the intel_dip.h file
>     instead of intel_display_devices.h (Jani)
>   - Make function names more descriptive and avoid overuse of multiple
>     acronyms. (Jani)
>
> Note:
>   - Though I have fixed the naming as suggested in most places, I
>     have retained HAS_EMP_AS_SDP_TL for the following reasons:
>     1) Lack of an apt name that avoids the acronym for
>        'Extended Metadata Packet Adaptive Sync Secondary Packet Transmission
>        Line'.
>     2) Keeping this name makes it easier to find and map with the exact name
>        for such a complex register name.
>
>     However, I am open to suggestions for a better name.
>
> Rev4:
>   - Drop the patch to check for DP encoder before writing EMP_AS_SDP_TL
>     register. Instead reset the register to 0 for non DP encoder case.
>
> Rev5:
>   - Rebase
>   - Address review comments from Suraj:
>   - Drop some redundant checks, and fix few commit messages.
>
> Rev6:
>   - Move the new struct in intel_display_types.h from intel_dip.h (Jani)
>   - Check for CMN_SDP_TL restriction and Warn if not followed. (Suraj)
>   - Use HAS_CMN_SDP_TL() instead of checking if cmn_sdp_tl is set or not.
>     (Sashiko)
>   - Make sure that the guardband is sufficient as per CMN_SDP_TL while
>     optiminzing the guardband.
>
> Rev7:
>   - Account for VSC SDP's own minimum guardband requirement in
>     intel_dp_sdp_min_guardband(), for completeness. (Sashiko)
>   - Wrap two long line macro definitions in intel_dip_regs.h.
>
> Ankit Nautiyal (13):
>    drm/i915/dip: Add new file to handle Data Island Packet hardware
>    drm/i915/vrr: Use the helper to write EMP_AS_SDP_TL register
>    drm/i915/intel_dip: Add check for DP encoder
>    drm/i915/dip: Add helper to get AS SDP Transmission Line
>    drm/i915/display: Add crtc state for DIP transmission lines
>    drm/i915/dip: Store and use AS SDP transmission line from crtc state
>    drm/i915/dip: Add HAS_COMMON_SDP_TL macro
>    drm/i915/dip: Store SDP transmission lines in crtc_state
>    drm/i915/dp: Introduce helpers to enable/disable CMN SDP Transmission
>      line
>    drm/i915/dip: Enable Common SDP Transmission line
>    drm/i915/dp: Account VSC SDP in min guardband
>    drm/i915/dp: Adjust SDP guardband requirement for CMN_SDP_TL
>    drm/i915/display: Dump DIP Transmission lines
>
> Arun R Murthy (1):
>    drm/i915/dip_regs: Add register definitions for common SDP
>      Transmission Line

Thanks for the review comments, and suggestions. Pushed to drm-intel-next.

intel_dip.c was introduced here but only covers the transmission-line 
handling. Two follow-ups remain:

- Extract the remaining low-level DIP buffer/infoframe code out of 
intel_hdmi.c into intel_dip.c.
- Introduce a DIP type enum so HDMI packet types and DP SDP types aren't 
mixed in the same namespace in hsw_infoframe_enable()

I'll try to get to that next.


Thanks & Regards,

Ankit

>
>   drivers/gpu/drm/i915/Makefile                 |   1 +
>   .../drm/i915/display/intel_crtc_state_dump.c  |   9 +
>   drivers/gpu/drm/i915/display/intel_ddi.c      |   5 +
>   drivers/gpu/drm/i915/display/intel_dip.c      | 215 ++++++++++++++++++
>   drivers/gpu/drm/i915/display/intel_dip.h      |  53 +++++
>   drivers/gpu/drm/i915/display/intel_dip_regs.h |  38 ++++
>   drivers/gpu/drm/i915/display/intel_display.c  |   6 +
>   .../drm/i915/display/intel_display_types.h    |  16 ++
>   drivers/gpu/drm/i915/display/intel_dp.c       |  62 ++++-
>   drivers/gpu/drm/i915/display/intel_vrr.c      |  14 +-
>   drivers/gpu/drm/i915/display/intel_vrr_regs.h |   6 -
>   drivers/gpu/drm/xe/Makefile                   |   1 +
>   12 files changed, 407 insertions(+), 19 deletions(-)
>   create mode 100644 drivers/gpu/drm/i915/display/intel_dip.c
>   create mode 100644 drivers/gpu/drm/i915/display/intel_dip.h
>   create mode 100644 drivers/gpu/drm/i915/display/intel_dip_regs.h
>