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The top_dp and top_edp muxes can be both parented to either TVDPLL1
or TVDPLL2, two identically specced PLLs for the specific purpose of
giving out pixel clock: this becomes a problem when the MediaTek
DisplayPort Interface (DPI) driver tries to set the pixel clock rate.
In the usecase of two simultaneous outputs (using two controllers),
it was seen that one of the displays would sometimes display garbled
output (if any at all) and this was because:
- top_edp was set to TVDPLL1, outputting X GHz
- top_dp was set to TVDPLL2, outputting Y GHz
- mtk_dpi calls clk_set_rate(top_edp, Z GHz)
- top_dp is switched to TVDPLL1
- TVDPLL1 changes its rate, top_edp outputs the wrong rate.
- eDP display is garbled
To solve this issue, remove all TVDPLL1 parents from `top_dp` and
all TVDPLL2 parents from `top_edp`, plus, necessarily switch both
clocks to use the new MUX_GATE_CLR_SET_UPD_INDEXED() macro to be
able to use the right bit index for the new parents list.
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20231103102533.69280-3-angelogioacchino.delregno@collabora.com
Reviewed-by: Fei Shao <fshao@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
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.