Commit c78b4a85 authored by Jani Nikula's avatar Jani Nikula
Browse files

drm/dp: add helper for extracting adjust 128b/132b TX FFE preset 



The DP 2.0 128b/132b channel coding uses TX FFE presets instead of
vswing and pre-emphasis.

Cc: dri-devel@lists.freedesktop.org
Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: default avatarMaxime Ripard <mripard@kernel.org>
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/4ba129c51aeb01a5f210de7026abe704a554a178.1631191763.git.jani.nikula@intel.com
parent 762520e3

drivers/gpu/drm/drm_dp_helper.c

+14 −0
Original line number Diff line number Diff line
@@ -130,6 +130,20 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI 
}

EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis);



/* DP 2.0 128b/132b */

u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],

				   int lane)

{

	int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);

	int s = ((lane & 1) ?

		 DP_ADJUST_TX_FFE_PRESET_LANE1_SHIFT :

		 DP_ADJUST_TX_FFE_PRESET_LANE0_SHIFT);

	u8 l = dp_link_status(link_status, i);



	return (l >> s) & 0xf;

}

EXPORT_SYMBOL(drm_dp_get_adjust_tx_ffe_preset);



u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],

					 unsigned int lane)

{

include/drm/drm_dp_helper.h

+2 −0
Original line number Diff line number Diff line
@@ -1494,6 +1494,8 @@ u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE], 
				     int lane);

u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE],

					  int lane);

u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],

				   int lane);

u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],

					 unsigned int lane);