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[why] 1. When HPD deassertion is pulled in the middle of enabe stream link training, we will abort current training and turn off PHY. This causes current link settings to be zeroed this causes later stream enablement sequence to fail as we prefer to carry on enablement process despite of link training failure for SST. 2. When HPD is toggled after detection before before the enable stream sequence as a result. There could be a race condition where we could end up enable stream based on the previous link even though the link is updated after the HPD toggle. This causes an issue where our link bandwidth is no longer enough to accommodate the timing therefore causes us to oversubscribe MST payload time slots. As discussed we decided to add basic sanity check to make sure that our code can handle the oversubscription failure silently without system hang. [how] 1. Keep PHY powered on when HPD is deasserted during enable stream and wait for the detection sequence to power it off later. 2. Do not allocate payload if the required timeslot for current timing is greater than 64 timeslots. Reviewed-by: Aric Cyr <Aric.Cyr@amd.com> Reviewed-by: George Shen <George.Shen@amd.com> Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com> Signed-off-by: Wenjing Liu <wenjing.liu@amd.com> Tested-by: Daniel Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.