On Thu, Oct 07, 2021 at 01:31:08PM +0300, Jani Nikula wrote:
> The 128b/132b channel coding link training uses more straightforward TX
> FFE preset values. Reuse voltage tries and max vswing for retry logic.
>
> The delays for 128b/132b are still all wrong, but this is regardless a
> step forward.
>
> v2: Fix UHBR rate checks, use intel_dp_is_uhbr() helper
>
> v3:
> - Rebase
> - Modify intel_dp_adjust_request_changed() and
> intel_dp_link_max_vswing_reached() to take 128b/132b into
> account. (Ville)
>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_ddi.c | 18 ++-
> .../drm/i915/display/intel_dp_link_training.c | 124 +++++++++++++-----
> 2 files changed, 106 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 3f7bbeb3e3cd..59428ce4f8c1 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -1338,13 +1338,20 @@ static int translate_signal_level(struct intel_dp *intel_dp,
> return 0;
> }
>
> -static int intel_ddi_dp_level(struct intel_dp *intel_dp, int lane)
> +static int intel_ddi_dp_level(struct intel_dp *intel_dp,
> + const struct intel_crtc_state *crtc_state,
> + int lane)
> {
> u8 train_set = intel_dp->train_set[lane];
> - u8 signal_levels = train_set & (DP_TRAIN_VOLTAGE_SWING_MASK |
> - DP_TRAIN_PRE_EMPHASIS_MASK);
>
> - return translate_signal_level(intel_dp, signal_levels);
> + if (intel_dp_is_uhbr(crtc_state)) {
> + return train_set & DP_TX_FFE_PRESET_VALUE_MASK;
BTW I just noticed dg2_get_snps_buf_trans() does not check for
HDMI vs. DP. Also it isn't using intel_dp_is_uhbr() and has
the > vs. >= bug in the open coded check.
> + } else {
> + u8 signal_levels = train_set & (DP_TRAIN_VOLTAGE_SWING_MASK |
> + DP_TRAIN_PRE_EMPHASIS_MASK);
> +
> + return translate_signal_level(intel_dp, signal_levels);
> + }
> }
>
> int intel_ddi_level(struct intel_encoder *encoder,
> @@ -1362,7 +1369,8 @@ int intel_ddi_level(struct intel_encoder *encoder,
> if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI))
> level = intel_ddi_hdmi_level(encoder, trans);
> else
> - level = intel_ddi_dp_level(enc_to_intel_dp(encoder), lane);
> + level = intel_ddi_dp_level(enc_to_intel_dp(encoder), crtc_state,
> + lane);
>
> if (drm_WARN_ON_ONCE(&i915->drm, level >= n_entries))
> level = n_entries - 1;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> index 1a943ae38a6b..c54b7df56c9f 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> @@ -304,11 +304,31 @@ static bool has_per_lane_signal_levels(struct intel_dp *intel_dp,
> return !intel_dp_phy_is_downstream_of_source(intel_dp, dp_phy);
> }
>
> -static u8 intel_dp_get_lane_adjust_train(struct intel_dp *intel_dp,
> - const struct intel_crtc_state *crtc_state,
> - enum drm_dp_phy dp_phy,
> - const u8 link_status[DP_LINK_STATUS_SIZE],
> - int lane)
> +
> +static u8 intel_dp_get_lane_adjust_train_128b132b(struct intel_dp *intel_dp,
> + const struct intel_crtc_state *crtc_state,
> + enum drm_dp_phy dp_phy,
> + const u8 link_status[DP_LINK_STATUS_SIZE],
> + int lane)
> +{
> + u8 tx_ffe = 0;
> +
> + if (has_per_lane_signal_levels(intel_dp, dp_phy)) {
> + lane = min(lane, crtc_state->lane_count - 1);
> + tx_ffe = drm_dp_get_adjust_tx_ffe_preset(link_status, lane);
> + } else {
> + for (lane = 0; lane < crtc_state->lane_count; lane++)
> + tx_ffe = max(tx_ffe, drm_dp_get_adjust_tx_ffe_preset(link_status, lane));
> + }
> +
> + return tx_ffe;
> +}
> +
> +static u8 intel_dp_get_lane_adjust_train_8b10b(struct intel_dp *intel_dp,
> + const struct intel_crtc_state *crtc_state,
> + enum drm_dp_phy dp_phy,
> + const u8 link_status[DP_LINK_STATUS_SIZE],
> + int lane)
> {
> u8 v = 0;
> u8 p = 0;
> @@ -340,6 +360,20 @@ static u8 intel_dp_get_lane_adjust_train(struct intel_dp *intel_dp,
> return v | p;
> }
>
> +static u8 intel_dp_get_lane_adjust_train(struct intel_dp *intel_dp,
> + const struct intel_crtc_state *crtc_state,
> + enum drm_dp_phy dp_phy,
> + const u8 link_status[DP_LINK_STATUS_SIZE],
> + int lane)
> +{
> + if (intel_dp_is_uhbr(crtc_state))
> + return intel_dp_get_lane_adjust_train_128b132b(intel_dp, crtc_state,
> + dp_phy, link_status, lane);
> + else
> + return intel_dp_get_lane_adjust_train_8b10b(intel_dp, crtc_state,
> + dp_phy, link_status, lane);
> +}
> +
> #define TRAIN_REQ_FMT "%d/%d/%d/%d"
> #define _TRAIN_REQ_VSWING_ARGS(link_status, lane) \
> (drm_dp_get_adjust_request_voltage((link_status), (lane)) >> DP_TRAIN_VOLTAGE_SWING_SHIFT)
^ those would need doing too
> @@ -464,6 +498,13 @@ intel_dp_program_link_training_pattern(struct intel_dp *intel_dp,
> _TRAIN_SET_PREEMPH_ARGS((train_set)[1]), \
> _TRAIN_SET_PREEMPH_ARGS((train_set)[2]), \
> _TRAIN_SET_PREEMPH_ARGS((train_set)[3])
> +#define _TRAIN_SET_TX_FFE_ARGS(train_set) \
> + ((train_set) & DP_TX_FFE_PRESET_VALUE_MASK), ""
Sure, why not.
> +#define TRAIN_SET_TX_FFE_ARGS(train_set) \
> + _TRAIN_SET_TX_FFE_ARGS((train_set)[0]), \
> + _TRAIN_SET_TX_FFE_ARGS((train_set)[1]), \
> + _TRAIN_SET_TX_FFE_ARGS((train_set)[2]), \
> + _TRAIN_SET_TX_FFE_ARGS((train_set)[3])
>
> void intel_dp_set_signal_levels(struct intel_dp *intel_dp,
> const struct intel_crtc_state *crtc_state,
> @@ -473,14 +514,23 @@ void intel_dp_set_signal_levels(struct intel_dp *intel_dp,
> struct drm_i915_private *i915 = to_i915(encoder->base.dev);
> char phy_name[10];
>
> - drm_dbg_kms(&i915->drm, "[ENCODER:%d:%s][%s] lanes: %d, "
> - "vswing levels: " TRAIN_SET_FMT ", "
> - "pre-emphasis levels: " TRAIN_SET_FMT "\n",
> - encoder->base.base.id, encoder->base.name,
> - intel_dp_phy_name(dp_phy, phy_name, sizeof(phy_name)),
> - crtc_state->lane_count,
> - TRAIN_SET_VSWING_ARGS(intel_dp->train_set),
> - TRAIN_SET_PREEMPH_ARGS(intel_dp->train_set));
> + if (intel_dp_is_uhbr(crtc_state)) {
> + drm_dbg_kms(&i915->drm, "[ENCODER:%d:%s][%s] lanes: %d, "
> + "128b/132b TX FFE presets: " TRAIN_SET_FMT "\n",
> + encoder->base.base.id, encoder->base.name,
> + intel_dp_phy_name(dp_phy, phy_name, sizeof(phy_name)),
> + crtc_state->lane_count,
> + TRAIN_SET_TX_FFE_ARGS(intel_dp->train_set));
> + } else {
> + drm_dbg_kms(&i915->drm, "[ENCODER:%d:%s][%s] lanes: %d, "
> + "vswing levels: " TRAIN_SET_FMT ", "
> + "pre-emphasis levels: " TRAIN_SET_FMT "\n",
> + encoder->base.base.id, encoder->base.name,
> + intel_dp_phy_name(dp_phy, phy_name, sizeof(phy_name)),
> + crtc_state->lane_count,
> + TRAIN_SET_VSWING_ARGS(intel_dp->train_set),
> + TRAIN_SET_PREEMPH_ARGS(intel_dp->train_set));
Wonder if we should say "8b/10b" here just to be super clear?
> + }
>
> if (intel_dp_phy_is_downstream_of_source(intel_dp, dp_phy))
> encoder->set_signal_levels(encoder, crtc_state);
> @@ -529,16 +579,22 @@ static bool intel_dp_link_max_vswing_reached(struct intel_dp *intel_dp,
> * 2+1 or 3+0 depending on whether vswing level 3 is supported or not.
> */
> for (lane = 0; lane < crtc_state->lane_count; lane++) {
> - u8 v = (intel_dp->train_set[lane] & DP_TRAIN_VOLTAGE_SWING_MASK) >>
> - DP_TRAIN_VOLTAGE_SWING_SHIFT;
> - u8 p = (intel_dp->train_set[lane] & DP_TRAIN_PRE_EMPHASIS_MASK) >>
> - DP_TRAIN_PRE_EMPHASIS_SHIFT;
> -
> - if ((intel_dp->train_set[lane] & DP_TRAIN_MAX_SWING_REACHED) == 0)
> - return false;
> -
> - if (v + p != 3)
> - return false;
> + if (intel_dp_is_uhbr(crtc_state)) {
> + if ((intel_dp->train_set[lane] & DP_TX_FFE_PRESET_VALUE_MASK) !=
> + DP_TX_FFE_PRESET_VALUE_MASK)
> + return false;
Seems sane. Maybe we shuld suck these little things into
128b/132b vs. 8b/10b specific helper function just to
declutter intel_dp_link_max_vswing_reached() a bit?
> + } else {
> + u8 v = (intel_dp->train_set[lane] & DP_TRAIN_VOLTAGE_SWING_MASK) >>
> + DP_TRAIN_VOLTAGE_SWING_SHIFT;
> + u8 p = (intel_dp->train_set[lane] & DP_TRAIN_PRE_EMPHASIS_MASK) >>
> + DP_TRAIN_PRE_EMPHASIS_SHIFT;
> +
> + if ((intel_dp->train_set[lane] & DP_TRAIN_MAX_SWING_REACHED) == 0)
> + return false;
> +
> + if (v + p != 3)
> + return false;
> + }
> }
>
> return true;
> @@ -601,17 +657,24 @@ static void intel_dp_link_training_clock_recovery_delay(struct intel_dp *intel_d
> drm_dp_lttpr_link_train_clock_recovery_delay();
> }
>
> -static bool intel_dp_adjust_request_changed(int lane_count,
> +static bool intel_dp_adjust_request_changed(const struct intel_crtc_state *crtc_state,
> const u8 old_link_status[DP_LINK_STATUS_SIZE],
> const u8 new_link_status[DP_LINK_STATUS_SIZE])
> {
> int lane;
>
> - for (lane = 0; lane < lane_count; lane++) {
> - u8 old = drm_dp_get_adjust_request_voltage(old_link_status, lane) |
> - drm_dp_get_adjust_request_pre_emphasis(old_link_status, lane);
> - u8 new = drm_dp_get_adjust_request_voltage(new_link_status, lane) |
> - drm_dp_get_adjust_request_pre_emphasis(new_link_status, lane);
> + for (lane = 0; lane < crtc_state->lane_count; lane++) {
> + u8 old, new;
> +
> + if (intel_dp_is_uhbr(crtc_state)) {
> + old = drm_dp_get_adjust_tx_ffe_preset(old_link_status, lane);
> + new = drm_dp_get_adjust_tx_ffe_preset(new_link_status, lane);
> + } else {
> + old = drm_dp_get_adjust_request_voltage(old_link_status, lane) |
> + drm_dp_get_adjust_request_pre_emphasis(old_link_status, lane);
> + new = drm_dp_get_adjust_request_voltage(new_link_status, lane) |
> + drm_dp_get_adjust_request_pre_emphasis(new_link_status, lane);
> + }
I like it.
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> if (old != new)
> return true;
> @@ -721,8 +784,7 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp,
> return false;
> }
>
> - if (!intel_dp_adjust_request_changed(crtc_state->lane_count,
> - old_link_status, link_status))
> + if (!intel_dp_adjust_request_changed(crtc_state, old_link_status, link_status))
> ++voltage_tries;
> else
> voltage_tries = 1;
> --
> 2.30.2
--
Ville Syrjälä
Intel
