From bf9cb3babcf7ea2f322119c70baaeaa1e97d21a3 Mon Sep 17 00:00:00 2001
From: Jani Nikula <jani.nikula@intel.com>
Date: Thu, 9 Sep 2021 15:51:56 +0300
Subject: drm/dp: add helper for extracting adjust 128b/132b TX FFE preset
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Git-commit: c78b4a85721f3905ba9baeac4e0bb99a36211d9b
Patch-mainline: v5.16-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
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
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/drm_dp_helper.c | 14 ++++++++++++++
include/drm/drm_dp_helper.h | 2 ++
2 files changed, 16 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 2e74b02ed96b..4d0d1e8e51fa 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -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)
{
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index f3a61341011d..3ee0b3ffb8a5 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -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);
--
2.38.1