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| author |   Ville Syrjälä <ville.syrjala@linux.intel.com> | 2020-05-12 20:41:43 +0300 |
|---|---|---|
| committer | Ville Syrjälä <ville.syrjala@linux.intel.com> | 2020-06-03 16:23:21 +0300 |
| commit | f6adb5f061954f0f859e47117665554504f7ec80 (patch) | |
| tree | 8716c98c9a37947e9197af5ad9ab04a737b14634 /drivers/gpu/drm/i915/display/intel_dp_mst.c | |
| parent | drm/i915: Add {preemph,voltage}_max() vfuncs (diff) | |
| download | wireguard-linux-f6adb5f061954f0f859e47117665554504f7ec80.tar.xz wireguard-linux-f6adb5f061954f0f859e47117665554504f7ec80.zip | |
drm/i915: Reverse preemph vs. voltage swing preference
The DP spec says:
"When the combination of the requested pre-emphasis level and
voltage swing exceeds the capability of a DPTX, the DPTX shall
set the pre-emphasis level according to the request and use the
highest voltage swing it can output with the given pre-emphasis level."
and
"When a DPTX reads a request beyond the limits of this Standard,
the DPTX shall set the pre-emphasis level according to the request
and set the highest voltage swing level it can output with the
given pre-emphasis level. If a DPTX is requested for 9.5dB of
pre-emphasis level (may be supported for a DPTX) and cannot support
that level, it shall set the pre-emphasis level to the next
highest level, 6dB."
Ie. we should first validate the pre-emphasis, and then select
the appropriate vswing for it.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200512174145.3186-6-ville.syrjala@linux.intel.com
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Diffstat (limited to 'drivers/gpu/drm/i915/display/intel_dp_mst.c')
0 files changed, 0 insertions, 0 deletions