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[Why] When we receive CSN message to notify one port is disconnected, we will implicitly set its corresponding num_slots to 0. Later on, we will eventually call drm_dp_update_payload_part1() to arrange down streams. In drm_dp_update_payload_part1(), we iterate over all proposed_vcpis[] to do the update. Not specific to a target sink only. For example, if we light up 2 monitors, Monitor_A and Monitor_B, and then we unplug Monitor_B. Later on, when we call drm_dp_update_payload_part1() to try to update payload for Monitor_A, we'll also implicitly clean payload for Monitor_B at the same time. And finally, when we try to call drm_dp_update_payload_part1() to clean payload for Monitor_B, we will do nothing at this time since payload for Monitor_B has been cleaned up previously. For StarTech 1to3 DP hub, it seems like if we didn't update DPCD payload ID table then polling for "ACT Handled"(BIT_1 of DPCD 002C0h) will fail and this polling will last for 3 seconds. Therefore, guess the best way is we don't set the proposed_vcpi[] diretly. Let user of these herlper functions to set the proposed_vcpi directly. [How] 1. Revert commit7617e9621b("drm/dp_mst: clear time slots for ports invalid") 2. Tackle the issue in previous commit by skipping those trasient proposed VCPIs. These stale VCPIs shoulde be explicitly cleared by user later on. Changes since v1: * Change debug macro to use drm_dbg_kms() instead * Amend the commit message to add Fixed & Cc tags Signed-off-by: Wayne Lin <Wayne.Lin@amd.com> Fixes:7617e9621b("drm/dp_mst: clear time slots for ports invalid") Cc: Lyude Paul <lyude@redhat.com> Cc: Wayne Lin <Wayne.Lin@amd.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: dri-devel@lists.freedesktop.org Cc: <stable@vger.kernel.org> # v5.5+ Signed-off-by: Lyude Paul <lyude@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210616035501.3776-2-Wayne.Lin@amd.com Reviewed-by: Lyude Paul <lyude@redhat.com>
Linux kernel
============
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In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
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Please read the Documentation/process/changes.rst file, as it contains the
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