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linux/include/drm/display
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Wayne Lin 69e90c1e33 drm/dp_mst: Fix drm RAD print 
[ Upstream commit 6bbce873a9 ]

[Why]
The RAD of sideband message printed today is incorrect.
For RAD stored within MST branch
- If MST branch LCT is 1, it's RAD array is untouched and remained as 0.
- If MST branch LCT is larger than 1, use nibble to store the up facing
  port number in cascaded sequence as illustrated below:

  u8 RAD[0] = (LCT_2_UFP << 4) | LCT_3_UFP
     RAD[1] = (LCT_4_UFP << 4) | LCT_5_UFP
     ...

In drm_dp_mst_rad_to_str(), it wrongly to use BIT_MASK(4) to fetch the port
number of one nibble.

[How]
Adjust the code by:
- RAD array items are valuable only for LCT >= 1.
- Use 0xF as the mask to replace BIT_MASK(4)

V2:
- Document how RAD is constructed (Imre)

V3:
- Adjust the comment for rad[] so kdoc formats it properly (Lyude)

Fixes: 2f015ec6ea ("drm/dp_mst: Add sideband down request tracing + selftests")
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Cc: Lyude Paul <lyude@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250113091100.3314533-2-Wayne.Lin@amd.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-04-10 14:39:13 +02:00
..
drm_dp.h drm: Fix DSC BPP increment decoding 2025-02-21 14:01:21 +01:00
drm_dp_aux_bus.h drm/dp: Add callbacks to make using DP AUX bus properly easier 2022-06-02 15:14:16 -07:00
drm_dp_dual_mode_helper.h drm: Rename dp/ to display/ 2022-04-25 11:17:45 +02:00
drm_dp_helper.h drm/dp: Describe target_rr_divider in struct drm_dp_as_sdp 2024-07-31 13:13:28 +02:00
drm_dp_mst_helper.h drm/dp_mst: Fix drm RAD print 2025-04-10 14:39:13 +02:00
drm_dp_tunnel.h drm/dp: Add support for DP tunneling 2024-02-27 17:34:10 +02:00
drm_dsc.h drm/i915/dp: Fix DSC line buffer depth programming 2024-04-19 17:05:35 +03:00
drm_dsc_helper.h drm/display/dsc: Add a helper to dump the DSC configuration 2024-07-03 18:05:12 +03:00
drm_hdcp.h drm/display: Move HDCP helpers into display-helper module 2022-04-25 11:19:36 +02:00
drm_hdcp_helper.h drm/display: Move HDCP helpers into display-helper module 2022-04-25 11:19:36 +02:00
drm_hdmi_helper.h drm/display: hdmi: Add HDMI compute clock helper 2024-05-28 10:12:25 +02:00
drm_hdmi_state_helper.h drm/connector: hdmi: shorten too long function name 2024-06-25 15:09:56 +03:00
drm_scdc.h drm/display: Move SCDC helpers into display-helper library 2022-04-25 11:19:37 +02:00
drm_scdc_helper.h drm/scdc-helper: Pimp SCDC debugs 2023-04-06 01:30:12 +03:00