drm/i915/dp: DPTX writes Swing/Pre-emphs(DPCD 0x103-0x106) requested during PHY Layer testing
Source needs to write DPCD 103-106 after receiving a PHY request to change swing/pre-emphasis after reading DPCD 206-207. This is especially needed if there is a retimer between source and sink and the retimer implements AUX_CH interception scheme to manage DP PHY settings (e.g. adjusting Swing/Pre-emphasis equalization level) for DP output channel. If the source doesn't write to DPCD 103-106, the retimer may not output the requested swing/pre-emphasis and eventually we fail compliance. v2: Rebase and use crtc->lane_count (Imre) Signed-off-by: Khaled Almahallawy <khaled.almahallawy@intel.com> Signed-off-by: Imre Deak <imre.deak@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210226081554.984307-1-khaled.almahallawy@intel.comReviewed-by: Imre Deak <imre.deak@intel.com> Signed-off-by: Imre Deak <imre.deak@intel.com>
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