On Wed, Aug 18, 2021 at 09:10:39PM +0300, Jani Nikula wrote:

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

Cc: dri-devel@lists.freedesktop.org Signed-off-by: Jani Nikula jani.nikula@intel.com

Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com

---

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 9389f92cb944..2843238a78e6 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);

-- 2.20.1