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

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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: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/4ba129c51aeb01a5f210de7026abe704a554a178.1631191763.git.jani.nikula@intel.com
This commit is contained in:
Jani Nikula 2021-09-09 15:51:56 +03:00
parent 762520e310
commit c78b4a8572
2 changed files with 16 additions and 0 deletions
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14
drivers/gpu/drm/drm_dp_helper.c
View File

@ -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)
{

2
include/drm/drm_dp_helper.h
View File

@ -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);