[Intel-gfx] [PATCH 7/7] drm/i915: Switch to LTTPR non-transparent mode link training
Imre Deak
imre.deak at intel.com
Tue Sep 22 18:26:54 UTC 2020
On Tue, Sep 22, 2020 at 08:37:44PM +0300, Ville Syrjälä wrote:
> On Tue, Sep 22, 2020 at 03:51:06PM +0300, Imre Deak wrote:
> > The DP Standard's recommendation is to use the LTTPR non-transparent
> > mode link training if LTTPRs are detected, so let's do this.
> >
> > Besides power-saving, the advantages of this are that the maximum number
> > of LTTPRs can only be used in non-transparent mode (the limit is 5-8 in
> > transparent mode), and it provides a way to narrow down the reason for a
> > link training failure to a given link segment. Non-transparent mode is
> > probably also the mode that was tested the most by the industry.
> >
> > The changes in this patchset:
> > - Pass the DP PHY that is currently link trained to all LT helpers, so
> > that these can access the correct LTTPR/DPRX DPCD registers.
> > - During LT take into account the LTTPR common lane rate/count and the
> > per LTTPR-PHY vswing/pre-emph limits.
> > - Switch to LTTPR non-transparent LT mode and train each link segment
> > according to the sequence in DP Standard v2.0 (complete CR/EQ for
> > each segment before continuing with the next segment).
> >
> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> > ---
> > .../drm/i915/display/intel_display_types.h | 1 +
> > drivers/gpu/drm/i915/display/intel_dp.c | 14 +-
> > .../drm/i915/display/intel_dp_link_training.c | 374 +++++++++++++++---
> > .../drm/i915/display/intel_dp_link_training.h | 10 +-
> > 4 files changed, 327 insertions(+), 72 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> > index b04921eba73b..2fb4e9a6a316 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > @@ -1281,6 +1281,7 @@ struct intel_dp {
> > u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE];
> > u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE];
> > u8 lttpr_common_caps[DP_LTTPR_COMMON_CAP_SIZE];
> > + u8 lttpr_phy_caps[DP_MAX_LTTPR_COUNT][DP_LTTPR_PHY_CAP_SIZE];
> > u8 fec_capable;
> > /* source rates */
> > int num_source_rates;
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index d88f327aa9ef..54ad31044eef 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -161,6 +161,7 @@ static void intel_dp_set_sink_rates(struct intel_dp *intel_dp)
> > 162000, 270000, 540000, 810000
> > };
> > int i, max_rate;
> > + int max_lttpr_rate;
> >
> > if (drm_dp_has_quirk(&intel_dp->desc, 0,
> > DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS)) {
> > @@ -174,6 +175,9 @@ static void intel_dp_set_sink_rates(struct intel_dp *intel_dp)
> > }
> >
> > max_rate = drm_dp_bw_code_to_link_rate(intel_dp->dpcd[DP_MAX_LINK_RATE]);
> > + max_lttpr_rate = drm_dp_lttpr_max_link_rate(intel_dp->lttpr_common_caps);
> > + if (max_lttpr_rate)
> > + max_rate = min(max_rate, max_lttpr_rate);
> >
> > for (i = 0; i < ARRAY_SIZE(dp_rates); i++) {
> > if (dp_rates[i] > max_rate)
> > @@ -219,6 +223,10 @@ static int intel_dp_max_common_lane_count(struct intel_dp *intel_dp)
> > int source_max = dig_port->max_lanes;
> > int sink_max = drm_dp_max_lane_count(intel_dp->dpcd);
> > int fia_max = intel_tc_port_fia_max_lane_count(dig_port);
> > + int lttpr_max = drm_dp_lttpr_max_lane_count(intel_dp->lttpr_common_caps);
> > +
> > + if (lttpr_max)
> > + sink_max = min(sink_max, lttpr_max);
> >
> > return min3(source_max, sink_max, fia_max);
> > }
> > @@ -5540,13 +5548,13 @@ void intel_dp_process_phy_request(struct intel_dp *intel_dp)
> > &intel_dp->compliance.test_data.phytest;
> > u8 link_status[DP_LINK_STATUS_SIZE];
> >
> > - if (!intel_dp_get_link_status(intel_dp, link_status)) {
> > + if (!intel_dp_get_link_status(intel_dp, DP_PHY_DPRX, link_status)) {
> > DRM_DEBUG_KMS("failed to get link status\n");
> > return;
> > }
> >
> > /* retrieve vswing & pre-emphasis setting */
> > - intel_dp_get_adjust_train(intel_dp, link_status);
> > + intel_dp_get_adjust_train(intel_dp, DP_PHY_DPRX, link_status);
> >
> > intel_dp_autotest_phy_ddi_disable(intel_dp);
> >
> > @@ -5701,7 +5709,7 @@ intel_dp_needs_link_retrain(struct intel_dp *intel_dp)
> > if (intel_psr_enabled(intel_dp))
> > return false;
> >
> > - if (!intel_dp_get_link_status(intel_dp, link_status))
> > + if (!intel_dp_get_link_status(intel_dp, DP_PHY_DPRX, link_status))
>
> Should we check all repeaters here too perhaps?
> I guess that should be a followup if we need it.
Hm, yea, would be better even if only for debugging; otherwise DPRX should have
a bad link if an LTTPR does.
>
> > return false;
> >
> > /*
> > 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 1485602659be..3aa685a9aa2a 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > @@ -25,6 +25,8 @@
> > #include "intel_dp.h"
> > #include "intel_dp_link_training.h"
> >
> > +#define DP_PHY_LTTPR(i) (DP_PHY_LTTPR1 + (i))
>
> Maybe just put that into drm_dp_helper.h?
Ok.
>
> > +
> > static void
> > intel_dp_dump_link_status(const u8 link_status[DP_LINK_STATUS_SIZE])
> > {
> > @@ -35,37 +37,140 @@ intel_dp_dump_link_status(const u8 link_status[DP_LINK_STATUS_SIZE])
> > }
> >
> > /**
> > - * intel_dp_get_link_status - get the link status information for the DPRX
> > + * intel_dp_get_link_status - get the link status information for a DP PHY
> > * @intel_dp: DP struct
> > + * @dp_phy: the DP PHY to get the link status for
> > * @link_status: buffer to return the status in
> > *
> > - * Fetch the AUX DPCD registers for the DPRX link status.
> > + * Fetch the AUX DPCD registers for the DPRX or an LTTPR PHY link status. The
> > + * layout of the returned @link_status matches the DPCD register layout of the
> > + * DPRX PHY link status.
> > *
> > * Returns true if the information was read successfully, false otherwise.
> > */
> > bool
> > -intel_dp_get_link_status(struct intel_dp *intel_dp, u8 link_status[DP_LINK_STATUS_SIZE])
> > +intel_dp_get_link_status(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy,
> > + u8 link_status[DP_LINK_STATUS_SIZE])
> > {
> > - return drm_dp_dpcd_read(&intel_dp->aux, DP_LANE0_1_STATUS, link_status,
> > - DP_LINK_STATUS_SIZE) == DP_LINK_STATUS_SIZE;
> > + u8 lttpr_status[DP_LINK_STATUS_SIZE - 1];
> > +
> > + if (dp_phy == DP_PHY_DPRX)
> > + return drm_dp_dpcd_read(&intel_dp->aux,
> > + DP_LANE0_1_STATUS,
> > + link_status,
> > + DP_LINK_STATUS_SIZE) == DP_LINK_STATUS_SIZE;
> > +
> > + if (drm_dp_dpcd_read(&intel_dp->aux,
> > + DP_LANE0_1_STATUS_PHY_REPEATER(dp_phy),
> > + lttpr_status,
> > + sizeof(lttpr_status)) != sizeof(lttpr_status))
> > + return false;
> > +
> > +#define link_reg(reg) link_status[(reg) - DP_LANE0_1_STATUS]
> > +#define lttpr_reg(reg) lttpr_status[(reg) - DP_LANE0_1_STATUS_PHY_REPEATER1]
> > +
> > + /* Convert the LTTPR to the sink PHY link status layout */
> > + link_reg(DP_LANE0_1_STATUS) = lttpr_reg(DP_LANE0_1_STATUS_PHY_REPEATER1);
> > + link_reg(DP_LANE2_3_STATUS) = lttpr_reg(DP_LANE2_3_STATUS_PHY_REPEATER1);
> > + link_reg(DP_LANE_ALIGN_STATUS_UPDATED) =
> > + lttpr_reg(DP_LANE_ALIGN_STATUS_UPDATED_PHY_REPEATER1);
> > + link_reg(DP_SINK_STATUS) = 0;
>
> So the difference is just the presence of the SINK_STATUS.
> Sad they couldn't be bothered to just stick a 0 placeholder
> there for lttprs.
Yes, could've been better designed.
>
> > + link_reg(DP_ADJUST_REQUEST_LANE0_1) =
> > + lttpr_reg(DP_ADJUST_REQUEST_LANE0_1_PHY_REPEATER1);
> > + link_reg(DP_ADJUST_REQUEST_LANE2_3) =
> > + lttpr_reg(DP_ADJUST_REQUEST_LANE2_3_PHY_REPEATER1);
> > +
> > +#undef link_reg
> > +#undef lttpr_reg
>
> Maybe this thing should be in the dp_helper as well? I could
> imagine other drivers wanting to do the same exactl thing
Ok, can add it to a new drm_dp_dpcd_read_phy_link_status() func, keeping the
exising users of drm_dp_dpcd_read_link_status() as-is.
>
> > +
> > + return true;
> > +}
> > +
> > +static int intel_dp_lttpr_count(struct intel_dp *intel_dp)
> > +{
> > + int count = drm_dp_lttpr_count(intel_dp->lttpr_common_caps);
> > +
> > + /*
> > + * Pretend no LTTPRs in case of LTTPR detection error, or
> > + * if too many (>8) LTTPRs are detected. This translates to link
> > + * training in transparent mode.
> > + */
> > + return count <= 0 ? 0 : count;
> > +}
> > +
> > +static const char *intel_dp_phy_name(enum drm_dp_phy dp_phy,
> > + char *buf, size_t buf_size)
> > +{
> > + if (dp_phy == DP_PHY_DPRX)
> > + snprintf(buf, buf_size, "DPRX");
> > + else
> > + snprintf(buf, buf_size, "LTTPR %d", dp_phy - DP_PHY_LTTPR1 + 1);
> > +
> > + return buf;
> > +}
> > +
> > +static uint8_t *intel_dp_lttpr_phy_caps(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > +{
> > + return &intel_dp->lttpr_phy_caps[dp_phy - DP_PHY_LTTPR1][0];
>
> Why the &...[0] ?
Just didn't realize the two ways are equivalent. Will remove the &..[0].
>
> > }
> >
> > /**
> > - * intel_dp_read_lttpr_caps - read the LTTPR common capabilities
> > + * intel_dp_read_lttpr_caps - read the LTTPR common and per-PHY capabilities
> > * @intel_dp: Intel DP struct
> > *
> > - * Read the LTTPR common capabilities.
> > + * Read the LTTPR common capabilities and the PHY capabilities for all
> > + * detected LTTPRs. In case of an LTTPR detection error or if the number of
> > + * LTTPRs is more than is supported (8), fall back to the no-LTTPR,
> > + * transparent mode link training mode.
> > */
> > void intel_dp_read_lttpr_caps(struct intel_dp *intel_dp)
> > {
> > + int lttpr_count;
> > + int i;
> > +
> > if (drm_dp_read_lttpr_common_caps(&intel_dp->aux,
> > - intel_dp->lttpr_common_caps) < 0)
> > + intel_dp->lttpr_common_caps) < 0) {
> > + memset(intel_dp->lttpr_common_caps, 0,
> > + sizeof(intel_dp->lttpr_common_caps));
> > return;
> > + }
> >
> > drm_dbg_kms(&dp_to_i915(intel_dp)->drm,
> > "LTTPR common capabilities: %*ph\n",
> > (int)sizeof(intel_dp->lttpr_common_caps),
> > intel_dp->lttpr_common_caps);
> > +
> > + lttpr_count = intel_dp_lttpr_count(intel_dp);
> > + /*
> > + * In case of unsupported number of LTTPRs fall-back to transparent
> > + * link training mode, still taking into account any LTTPR common
> > + * lane- rate/count limits.
> > + */
> > + if (lttpr_count <= 0)
> > + return;
> > +
> > + for (i = 0; i < lttpr_count; i++) {
> > + enum drm_dp_phy dp_phy = DP_PHY_LTTPR(i);
> > + uint8_t *phy_caps = intel_dp_lttpr_phy_caps(intel_dp, dp_phy);
> > + char phy_name[10];
> > +
> > + intel_dp_phy_name(dp_phy, phy_name, sizeof(phy_name));
> > +
> > + if (drm_dp_read_lttpr_phy_caps(&intel_dp->aux, dp_phy, phy_caps) < 0) {
> > + drm_dbg_kms(&dp_to_i915(intel_dp)->drm,
> > + "failed to read the PHY caps for %s\n",
> > + phy_name);
> > + continue;
> > + }
> > +
> > + drm_dbg_kms(&dp_to_i915(intel_dp)->drm,
> > + "%s PHY capabilities: %*ph\n",
> > + phy_name,
> > + (int)sizeof(intel_dp->lttpr_phy_caps[0]),
> > + phy_caps);
> > + }
> > }
> >
> > static u8 dp_voltage_max(u8 preemph)
> > @@ -83,10 +188,78 @@ static u8 dp_voltage_max(u8 preemph)
> > }
> > }
> >
> > +static u8 intel_dp_lttpr_voltage_max(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > +{
> > + const uint8_t *phy_caps = intel_dp_lttpr_phy_caps(intel_dp, dp_phy);
> > +
> > + if (drm_dp_lttpr_voltage_swing_level_3_supported(phy_caps))
> > + return DP_TRAIN_VOLTAGE_SWING_LEVEL_3;
> > + else
> > + return DP_TRAIN_VOLTAGE_SWING_LEVEL_2;
> > +}
> > +
> > +static u8 intel_dp_lttpr_preemph_max(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > +{
> > + const uint8_t *phy_caps = intel_dp_lttpr_phy_caps(intel_dp, dp_phy);
> > +
> > + if (drm_dp_lttpr_pre_emphasis_level_3_supported(phy_caps))
> > + return DP_TRAIN_PRE_EMPH_LEVEL_3;
> > + else
> > + return DP_TRAIN_PRE_EMPH_LEVEL_2;
> > +}
> > +
> > +static u8 intel_dp_phy_voltage_max(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > +{
> > + struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > + int lttpr_count = intel_dp_lttpr_count(intel_dp);
> > + u8 voltage_max;
> > +
> > + /*
> > + * Get voltage_max from the DPTX_PHY (source or LTTPR) upstream from
> > + * the DPRX_PHY we train.
> > + */
> > + if (lttpr_count == 0 || dp_phy == DP_PHY_LTTPR(lttpr_count - 1))
>
> phy_is_downstream_of_source() or somesuch helper maybe?
> There must be a better name than that though. But as usual
> I can't think of one right now.
Ok, can add an intel_dp_phy_is_downstream_of_source() helper.
>
> > + voltage_max = intel_dp->voltage_max(intel_dp);
> > + else
> > + voltage_max = intel_dp_lttpr_voltage_max(intel_dp, dp_phy + 1);
> > +
> > + drm_WARN_ON_ONCE(&i915->drm,
> > + voltage_max != DP_TRAIN_VOLTAGE_SWING_LEVEL_2 &&
> > + voltage_max != DP_TRAIN_VOLTAGE_SWING_LEVEL_3);
> > +
> > + return voltage_max;
> > +}
> > +
> > +static u8 intel_dp_phy_preemph_max(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > +{
> > + struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > + int lttpr_count = intel_dp_lttpr_count(intel_dp);
> > + u8 preemph_max;
> > +
> > + /*
> > + * Get preemph_max from the DPTX_PHY (source or LTTPR) upstream from
> > + * the DPRX_PHY we train.
> > + */
> > + if (lttpr_count == 0 || dp_phy == DP_PHY_LTTPR(lttpr_count - 1))
> > + preemph_max = intel_dp->preemph_max(intel_dp);
> > + else
> > + preemph_max = intel_dp_lttpr_preemph_max(intel_dp, dp_phy + 1);
> > +
> > + drm_WARN_ON_ONCE(&i915->drm,
> > + preemph_max != DP_TRAIN_PRE_EMPH_LEVEL_2 &&
> > + preemph_max != DP_TRAIN_PRE_EMPH_LEVEL_3);
> > +
> > + return preemph_max;
> > +}
> > +
> > void intel_dp_get_adjust_train(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy,
> > const u8 link_status[DP_LINK_STATUS_SIZE])
> > {
> > - struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > u8 v = 0;
> > u8 p = 0;
> > int lane;
> > @@ -98,21 +271,13 @@ void intel_dp_get_adjust_train(struct intel_dp *intel_dp,
> > p = max(p, drm_dp_get_adjust_request_pre_emphasis(link_status, lane));
> > }
> >
> > - preemph_max = intel_dp->preemph_max(intel_dp);
> > - drm_WARN_ON_ONCE(&i915->drm,
> > - preemph_max != DP_TRAIN_PRE_EMPH_LEVEL_2 &&
> > - preemph_max != DP_TRAIN_PRE_EMPH_LEVEL_3);
> > -
> > + preemph_max = intel_dp_phy_preemph_max(intel_dp, dp_phy);
> > if (p >= preemph_max)
> > p = preemph_max | DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
> >
> > v = min(v, dp_voltage_max(p));
> >
> > - voltage_max = intel_dp->voltage_max(intel_dp);
> > - drm_WARN_ON_ONCE(&i915->drm,
> > - voltage_max != DP_TRAIN_VOLTAGE_SWING_LEVEL_2 &&
> > - voltage_max != DP_TRAIN_VOLTAGE_SWING_LEVEL_3);
> > -
> > + voltage_max = intel_dp_phy_voltage_max(intel_dp, dp_phy);
> > if (v >= voltage_max)
> > v = voltage_max | DP_TRAIN_MAX_SWING_REACHED;
> >
> > @@ -120,17 +285,24 @@ void intel_dp_get_adjust_train(struct intel_dp *intel_dp,
> > intel_dp->train_set[lane] = v | p;
> > }
> >
> > -static bool intel_dp_disable_dpcd_training_pattern(struct intel_dp *intel_dp)
> > +static bool intel_dp_disable_dpcd_training_pattern(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > {
> > + int reg = dp_phy == DP_PHY_DPRX ?
> > + DP_TRAINING_PATTERN_SET :
> > + DP_TRAINING_PATTERN_SET_PHY_REPEATER(dp_phy);
> > u8 val = DP_TRAINING_PATTERN_DISABLE;
> >
> > - return drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_PATTERN_SET, &val, 1) == 1;
> > + return drm_dp_dpcd_write(&intel_dp->aux, reg, &val, 1) == 1;
> > }
> >
> > static bool
> > -intel_dp_set_link_train(struct intel_dp *intel_dp,
> > +intel_dp_set_link_train(struct intel_dp *intel_dp, enum drm_dp_phy dp_phy,
> > u8 dp_train_pat)
> > {
> > + int reg = dp_phy == DP_PHY_DPRX ?
> > + DP_TRAINING_PATTERN_SET :
> > + DP_TRAINING_PATTERN_SET_PHY_REPEATER(dp_phy);
> > u8 buf[sizeof(intel_dp->train_set) + 1];
> > int len;
> >
> > @@ -139,34 +311,36 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
> > if ((dp_train_pat & ~DP_LINK_SCRAMBLING_DISABLE) ==
> > DP_TRAINING_PATTERN_DISABLE)
> > /* don't write DP_TRAINING_LANEx_SET on disable */
> > - return intel_dp_disable_dpcd_training_pattern(intel_dp);
> > + return intel_dp_disable_dpcd_training_pattern(intel_dp, dp_phy);
> >
> > buf[0] = dp_train_pat;
> > /* DP_TRAINING_LANEx_SET follow DP_TRAINING_PATTERN_SET */
> > memcpy(buf + 1, intel_dp->train_set, intel_dp->lane_count);
> > len = intel_dp->lane_count + 1;
> >
> > - return drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_PATTERN_SET,
> > - buf, len) == len;
> > + return drm_dp_dpcd_write(&intel_dp->aux, reg, buf, len) == len;
> > }
> >
> > static bool
> > -intel_dp_reset_link_train(struct intel_dp *intel_dp,
> > +intel_dp_reset_link_train(struct intel_dp *intel_dp, enum drm_dp_phy dp_phy,
> > u8 dp_train_pat)
> > {
> > memset(intel_dp->train_set, 0, sizeof(intel_dp->train_set));
> > intel_dp_set_signal_levels(intel_dp);
> > - return intel_dp_set_link_train(intel_dp, dp_train_pat);
> > + return intel_dp_set_link_train(intel_dp, dp_phy, dp_train_pat);
> > }
> >
> > static bool
> > -intel_dp_update_link_train(struct intel_dp *intel_dp)
> > +intel_dp_update_link_train(struct intel_dp *intel_dp, enum drm_dp_phy dp_phy)
> > {
> > + int reg = dp_phy == DP_PHY_DPRX ?
> > + DP_TRAINING_LANE0_SET :
> > + DP_TRAINING_LANE0_SET_PHY_REPEATER(dp_phy);
> > int ret;
> >
> > intel_dp_set_signal_levels(intel_dp);
> >
> > - ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_LANE0_SET,
> > + ret = drm_dp_dpcd_write(&intel_dp->aux, reg,
> > intel_dp->train_set, intel_dp->lane_count);
> >
> > return ret == intel_dp->lane_count;
> > @@ -226,9 +400,22 @@ static void intel_dp_prepare_link_train(struct intel_dp *intel_dp)
> > intel_dp->DP |= DP_PORT_EN;
> > }
> >
> > -/* Perform the link training clock recovery phase using training pattern 1. */
> > +static void intel_dp_link_training_clock_recovery_delay(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > +{
> > + if (dp_phy == DP_PHY_DPRX)
> > + drm_dp_link_train_clock_recovery_delay(intel_dp->dpcd);
> > + else
> > + drm_dp_lttpr_link_train_clock_recovery_delay();
> > +}
> > +
> > +/*
> > + * Perform the link training clock recovery phase on the given DP PHY using
> > + * training pattern 1.
> > + */
> > static bool
> > -intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
> > +intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > {
> > struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > u8 voltage;
> > @@ -236,7 +423,7 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
> > bool max_vswing_reached = false;
> >
> > /* clock recovery */
> > - if (!intel_dp_reset_link_train(intel_dp,
> > + if (!intel_dp_reset_link_train(intel_dp, dp_phy,
> > DP_TRAINING_PATTERN_1 |
> > DP_LINK_SCRAMBLING_DISABLE)) {
> > drm_err(&i915->drm, "failed to enable link training\n");
> > @@ -260,9 +447,9 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
> > for (cr_tries = 0; cr_tries < max_cr_tries; ++cr_tries) {
> > u8 link_status[DP_LINK_STATUS_SIZE];
> >
> > - drm_dp_link_train_clock_recovery_delay(intel_dp->dpcd);
> > + intel_dp_link_training_clock_recovery_delay(intel_dp, dp_phy);
> >
> > - if (!intel_dp_get_link_status(intel_dp, link_status)) {
> > + if (!intel_dp_get_link_status(intel_dp, dp_phy, link_status)) {
> > drm_err(&i915->drm, "failed to get link status\n");
> > return false;
> > }
> > @@ -286,8 +473,8 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
> > voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
> >
> > /* Update training set as requested by target */
> > - intel_dp_get_adjust_train(intel_dp, link_status);
> > - if (!intel_dp_update_link_train(intel_dp)) {
> > + intel_dp_get_adjust_train(intel_dp, dp_phy, link_status);
> > + if (!intel_dp_update_link_train(intel_dp, dp_phy)) {
> > drm_err(&i915->drm,
> > "failed to update link training\n");
> > return false;
> > @@ -313,7 +500,8 @@ intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
> > * or for 1.4 devices that support it, training Pattern 3 for HBR2
> > * or 1.2 devices that support it, Training Pattern 2 otherwise.
> > */
> > -static u32 intel_dp_training_pattern(struct intel_dp *intel_dp)
> > +static u32 intel_dp_training_pattern(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > {
> > bool source_tps3, sink_tps3, source_tps4, sink_tps4;
> >
> > @@ -322,9 +510,11 @@ static u32 intel_dp_training_pattern(struct intel_dp *intel_dp)
> > * for all downstream devices that support HBR3. There are no known eDP
> > * panels that support TPS4 as of Feb 2018 as per VESA eDP_v1.4b_E1
> > * specification.
> > + * LTTPRs must support TPS4.
> > */
> > source_tps4 = intel_dp_source_supports_hbr3(intel_dp);
> > - sink_tps4 = drm_dp_tps4_supported(intel_dp->dpcd);
> > + sink_tps4 = dp_phy != DP_PHY_DPRX ||
> > + drm_dp_tps4_supported(intel_dp->dpcd);
> > if (source_tps4 && sink_tps4) {
> > return DP_TRAINING_PATTERN_4;
> > } else if (intel_dp->link_rate == 810000) {
> > @@ -341,7 +531,8 @@ static u32 intel_dp_training_pattern(struct intel_dp *intel_dp)
> > * all sinks follow the spec.
> > */
> > source_tps3 = intel_dp_source_supports_hbr2(intel_dp);
> > - sink_tps3 = drm_dp_tps3_supported(intel_dp->dpcd);
> > + sink_tps3 = dp_phy != DP_PHY_DPRX ||
> > + drm_dp_tps3_supported(intel_dp->dpcd);
> > if (source_tps3 && sink_tps3) {
> > return DP_TRAINING_PATTERN_3;
> > } else if (intel_dp->link_rate >= 540000) {
> > @@ -356,12 +547,27 @@ static u32 intel_dp_training_pattern(struct intel_dp *intel_dp)
> > return DP_TRAINING_PATTERN_2;
> > }
> >
> > +static void
> > +intel_dp_link_training_channel_equalization_delay(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > +{
> > + if (dp_phy == DP_PHY_DPRX) {
> > + drm_dp_link_train_channel_eq_delay(intel_dp->dpcd);
> > + } else {
> > + const uint8_t *phy_caps = intel_dp_lttpr_phy_caps(intel_dp, dp_phy);
> > +
> > + drm_dp_lttpr_link_train_channel_eq_delay(phy_caps);
> > + }
> > +}
> > +
> > /*
> > - * Perform the link training channel equalization phase using one of training
> > - * pattern 2, 3 or 4 depending on the the source and sink capabilities.
> > + * Perform the link training channel equalization phase on the given DP PHY
> > + * using one of training pattern 2, 3 or 4 depending on the the source and
> > + * sink capabilities.
> > */
> > static bool
> > -intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
> > +intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp,
> > + enum drm_dp_phy dp_phy)
> > {
> > struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > int tries;
> > @@ -369,22 +575,21 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
> > u8 link_status[DP_LINK_STATUS_SIZE];
> > bool channel_eq = false;
> >
> > - training_pattern = intel_dp_training_pattern(intel_dp);
> > + training_pattern = intel_dp_training_pattern(intel_dp, dp_phy);
> > /* Scrambling is disabled for TPS2/3 and enabled for TPS4 */
> > if (training_pattern != DP_TRAINING_PATTERN_4)
> > training_pattern |= DP_LINK_SCRAMBLING_DISABLE;
> >
> > /* channel equalization */
> > - if (!intel_dp_set_link_train(intel_dp,
> > - training_pattern)) {
> > + if (!intel_dp_set_link_train(intel_dp, dp_phy, training_pattern)) {
> > drm_err(&i915->drm, "failed to start channel equalization\n");
> > return false;
> > }
> >
> > for (tries = 0; tries < 5; tries++) {
> > -
> > - drm_dp_link_train_channel_eq_delay(intel_dp->dpcd);
> > - if (!intel_dp_get_link_status(intel_dp, link_status)) {
> > + intel_dp_link_training_channel_equalization_delay(intel_dp,
> > + dp_phy);
> > + if (!intel_dp_get_link_status(intel_dp, dp_phy, link_status)) {
> > drm_err(&i915->drm,
> > "failed to get link status\n");
> > break;
> > @@ -409,8 +614,8 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
> > }
> >
> > /* Update training set as requested by target */
> > - intel_dp_get_adjust_train(intel_dp, link_status);
> > - if (!intel_dp_update_link_train(intel_dp)) {
> > + intel_dp_get_adjust_train(intel_dp, dp_phy, link_status);
> > + if (!intel_dp_update_link_train(intel_dp, dp_phy)) {
> > drm_err(&i915->drm,
> > "failed to update link training\n");
> > break;
> > @@ -424,8 +629,6 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
> > "Channel equalization failed 5 times\n");
> > }
> >
> > - intel_dp_set_idle_link_train(intel_dp);
> > -
> > return channel_eq;
> >
> > }
> > @@ -442,34 +645,33 @@ intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
> > void intel_dp_stop_link_train(struct intel_dp *intel_dp)
> > {
> > intel_dp->link_trained = true;
> > -
> > - intel_dp_set_link_train(intel_dp,
> > + intel_dp_set_link_train(intel_dp, DP_PHY_DPRX,
> > DP_TRAINING_PATTERN_DISABLE);
> > }
> >
> > static bool
> > -intel_dp_link_train(struct intel_dp *intel_dp)
> > +intel_dp_link_train_phy(struct intel_dp *intel_dp, enum drm_dp_phy dp_phy)
> > {
> > struct intel_connector *intel_connector = intel_dp->attached_connector;
> > + char phy_name[10];
> > bool ret = false;
> >
> > - intel_dp_prepare_link_train(intel_dp);
> > -
> > - if (!intel_dp_link_training_clock_recovery(intel_dp))
> > + if (!intel_dp_link_training_clock_recovery(intel_dp, dp_phy))
> > goto out;
> >
> > - if (!intel_dp_link_training_channel_equalization(intel_dp))
> > + if (!intel_dp_link_training_channel_equalization(intel_dp, dp_phy))
> > goto out;
> >
> > ret = true;
> >
> > out:
> > drm_dbg_kms(&dp_to_i915(intel_dp)->drm,
> > - "[CONNECTOR:%d:%s] Link Training %s at Link Rate = %d, Lane count = %d",
> > + "[CONNECTOR:%d:%s] Link Training %s at Link Rate = %d, Lane count = %d, at %s",
> > intel_connector->base.base.id,
> > intel_connector->base.name,
> > ret ? "passed" : "failed",
> > - intel_dp->link_rate, intel_dp->lane_count);
> > + intel_dp->link_rate, intel_dp->lane_count,
> > + intel_dp_phy_name(dp_phy, phy_name, sizeof(phy_name)));
> >
> > return ret;
> > }
> > @@ -492,6 +694,33 @@ static void intel_dp_schedule_fallback_link_training(struct intel_dp *intel_dp)
> > schedule_work(&intel_connector->modeset_retry_work);
> > }
> >
> > +/* Perform the link training on all LTTPRs and the DPRX on a link. */
> > +static bool
> > +intel_dp_link_train_all_phys(struct intel_dp *intel_dp, int lttpr_count)
> > +{
> > + bool ret = true;
> > + int i;
> > +
> > + intel_dp_prepare_link_train(intel_dp);
> > +
> > + for (i = lttpr_count - 1; i >= 0; i--) {
> > + enum drm_dp_phy dp_phy = DP_PHY_LTTPR(i);
> > +
> > + ret = intel_dp_link_train_phy(intel_dp, dp_phy);
> > + intel_dp_disable_dpcd_training_pattern(intel_dp, dp_phy);
> > +
> > + if (!ret)
> > + break;
> > + }
> > +
> > + if (ret)
> > + intel_dp_link_train_phy(intel_dp, DP_PHY_DPRX);
> > +
> > + intel_dp_set_idle_link_train(intel_dp);
> > +
> > + return ret;
> > +}
> > +
> > static bool
> > intel_dp_set_lttpr_transparent_mode(struct intel_dp *intel_dp, bool enable)
> > {
> > @@ -501,10 +730,12 @@ intel_dp_set_lttpr_transparent_mode(struct intel_dp *intel_dp, bool enable)
> > return drm_dp_dpcd_write(&intel_dp->aux, DP_PHY_REPEATER_MODE, &val, 1) == 1;
> > }
> >
> > -static void intel_dp_init_lttpr_mode(struct intel_dp *intel_dp)
> > +static int intel_dp_init_lttpr_mode(struct intel_dp *intel_dp)
> > {
> > + int lttpr_count;
> > +
> > if (intel_dp_is_edp(intel_dp))
> > - return;
> > + return 0;
> >
> > /*
> > * TODO: the following re-reading of LTTPR caps can be removed
> > @@ -512,6 +743,19 @@ static void intel_dp_init_lttpr_mode(struct intel_dp *intel_dp)
> > */
> > intel_dp_read_lttpr_caps(intel_dp);
> > intel_dp_set_lttpr_transparent_mode(intel_dp, true);
> > +
> > + lttpr_count = intel_dp_lttpr_count(intel_dp);
> > + if (lttpr_count) {
> > + /*
> > + * If we can't set non-transparent mode fall-back to
> > + * transparent mode, still taking into account any LTTPR
> > + * common lane rate and count limits.
> > + */
> > + if (!intel_dp_set_lttpr_transparent_mode(intel_dp, false))
>
> Is there some magic to the double true+false transparent mode
> set here? Or just convenience?
Nope, v2.0 3.6.6.1 without explaining the reason:
"""
Before performing link training with LTTPR(s), the DPTX may place the LTTPR(s) in
Non-transparent mode by first writing 55h to the PHY_REPEATER_MODE register, and
then writing AAh.
"""
>
> In general looks good, and didn't require too much rewriting which is
> nice.
> Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> > + lttpr_count = 0;
> > + }
> > +
> > + return lttpr_count;
> > }
> >
> > /**
> > @@ -525,8 +769,8 @@ static void intel_dp_init_lttpr_mode(struct intel_dp *intel_dp)
> > */
> > void intel_dp_start_link_train(struct intel_dp *intel_dp)
> > {
> > - intel_dp_init_lttpr_mode(intel_dp);
> > + int lttpr_count = intel_dp_init_lttpr_mode(intel_dp);
> >
> > - if (!intel_dp_link_train(intel_dp))
> > + if (!intel_dp_link_train_all_phys(intel_dp, lttpr_count))
> > intel_dp_schedule_fallback_link_training(intel_dp);
> > }
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.h b/drivers/gpu/drm/i915/display/intel_dp_link_training.h
> > index c0be3ff709a0..d0393b76ffc1 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.h
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.h
> > @@ -10,12 +10,14 @@
> >
> > struct intel_dp;
> >
> > -bool intel_dp_get_link_status(struct intel_dp *intel_dp,
> > - u8 link_status[DP_LINK_STATUS_SIZE]);
> > +bool
> > +intel_dp_get_link_status(struct intel_dp *intel_dp, enum drm_dp_phy dp_phy,
> > + u8 link_status[DP_LINK_STATUS_SIZE]);
> > void intel_dp_read_lttpr_caps(struct intel_dp *intel_dp);
> >
> > -void intel_dp_get_adjust_train(struct intel_dp *intel_dp,
> > - const u8 link_status[DP_LINK_STATUS_SIZE]);
> > +void
> > +intel_dp_get_adjust_train(struct intel_dp *intel_dp, enum drm_dp_phy dp_phy,
> > + const u8 link_status[DP_LINK_STATUS_SIZE]);
> > void intel_dp_start_link_train(struct intel_dp *intel_dp);
> > void intel_dp_stop_link_train(struct intel_dp *intel_dp);
> >
> > --
> > 2.17.1
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Ville Syrjälä
> Intel
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