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TGL is suffering of timeouts and fifo underruns when disabling transcoder in MST mode, this is fixed by set TRANS_DDI_MODE_SELECT to 0(HDMI mode) when clearing DDI select. Although BSpec disable sequence don't require this step, it is a harmless change and it is also done by Windows driver. Anyhow HW team was notified about that but it can take some time to documentation to be updated. A case that always lead to those issues is: - do a modeset enabling pipe A and pipe B in the same MST stream leaving A as master - disable pipe A, promote B as master doing a full modeset in A - enable pipe A, changing the master transcoder back to A(doing a full modeset in B) - Pow: underruns and timeouts The transcoders involved will only work again when complete disabled and their power wells turned off causing a reset in their registers. v2: Setting TRANS_DDI_MODE_SELECT to default when clearing DDI select not anymore when disabling TRANS_DDI, both work but this one looks more safe. (Ville comment) Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: José Roberto de Souza <jose.souza@intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200203225549.152301-1-jose.souza@intel.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.