[Intel-gfx] [PATCHv7 5/5] drm/i915/dp: Enable Upfront link training for typeC DP support on BXT
Jim Bride
jim.bride at linux.intel.com
Wed Jul 27 17:51:44 UTC 2016
On Wed, Jul 27, 2016 at 11:20:18AM +0000, R, Durgadoss wrote:
> > -----Original Message-----
> > From: Ville Syrjälä [mailto:ville.syrjala at linux.intel.com]
> > Sent: Wednesday, July 27, 2016 3:28 PM
> > To: R, Durgadoss <durgadoss.r at intel.com>
> > Cc: intel-gfx at lists.freedesktop.org; Conselvan De Oliveira, Ander
> > <ander.conselvan.de.oliveira at intel.com>; Bride, Jim <jim.bride at intel.com>;
> > Navare, Manasi D <manasi.d.navare at intel.com>
> > Subject: Re: [PATCHv7 5/5] drm/i915/dp: Enable Upfront link training for
> > typeC DP support on BXT
> >
> > On Wed, Jul 13, 2016 at 04:15:44PM +0530, Durgadoss R wrote:
> > > To support USB type C alternate DP mode, the display driver needs to
> > > know the number of lanes required by the DP panel as well as number
> > > of lanes that can be supported by the type-C cable. Sometimes, the
> > > type-C cable may limit the bandwidth even if Panel can support
> > > more lanes. To address these scenarios, the display driver will
> > > start link training with max lanes, and if that fails, the driver
> > > falls back to x2 lanes; and repeats this procedure for all
> > > bandwidth/lane configurations.
> > >
> > > * Since link training is done before modeset only the port
> > > (and not pipe/planes) and its associated PLLs are enabled.
> > > * On DP hotplug: Directly start link training on the DP encoder.
> > > * On Connected boot scenarios: When booted with an LFP and a DP,
> > > sometimes BIOS brings up DP. In these cases, we disable the
> > > crtc and then do upfront link training; and bring it back up.
> > > * All local changes made for upfront link training are reset
> > > to their previous values once it is done; so that the
> > > subsequent modeset is not aware of these changes.
> > >
> > > Changes since v6:
> > > * Fix some initialization bugs on link_rate (Jim Bride)
> > > * Use link_rate (and not link_bw) for upfront (Ville)
> > > * Make intel_dp_upfront*() as a vfunc (Ander)
> > > * The train_set_valid variable in intel_dp was removed due to
> > > issues in fast link training. So, to indicate the link train
> > > status, move the channel_eq inside intel_dp.
> > > Changes since v5:
> > > * Moved retry logic in upfront to intel_dp.c so that it
> > > can be used for all platforms.
> > > Changes since v4:
> > > * Removed usage of crtc_state in upfront link training;
> > > Hence no need to find free crtc to do upfront now.
> > > * Re-enable crtc if it was disabled for upfront.
> > > * Use separate variables to track max lane count
> > > and link rate found by upfront, without modifying
> > > the original DPCD read from panel.
> > > Changes since v3:
> > > * Fixed a return value on BXT check
> > > * Reworked on top of bxt_ddi_pll_select split from Ander
> > > * Renamed from ddi_upfront to bxt_upfront since the
> > > upfront logic includes BXT specific functions for now.
> > > Changes since v2:
> > > * Rebased on top of latest dpll_mgr.c code and
> > > latest HPD related clean ups.
> > > * Corrected return values from upfront (Ander)
> > > * Corrected atomic locking for upfront in intel_dp.c (Ville)
> > > Changes since v1:
> > > * all pll related functions inside ddi.c
> > >
> > > Signed-off-by: Durgadoss R <durgadoss.r at intel.com>
> > > ---
> > > drivers/gpu/drm/i915/intel_ddi.c | 45 ++++++++
> > > drivers/gpu/drm/i915/intel_dp.c | 155
> > +++++++++++++++++++++++++-
> > > drivers/gpu/drm/i915/intel_dp_link_training.c | 7 +-
> > > drivers/gpu/drm/i915/intel_drv.h | 15 +++
> > > 4 files changed, 213 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_ddi.c
> > b/drivers/gpu/drm/i915/intel_ddi.c
> > > index ab1745a..3bad01b 100644
> > > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > > @@ -2356,6 +2356,51 @@ intel_ddi_init_hdmi_connector(struct
> > intel_digital_port *intel_dig_port)
> > > return connector;
> > > }
> > >
> > > +bool intel_bxt_upfront_link_train(struct intel_dp *intel_dp,
> > > + int clock, uint8_t lane_count)
> > > +{
> > > + struct intel_connector *connector = intel_dp->attached_connector;
> > > + struct intel_encoder *encoder = connector->encoder;
> > > + struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> > > + struct intel_shared_dpll *pll;
> > > + struct intel_shared_dpll_config tmp_pll_config;
> > > + struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> > > + enum intel_dpll_id dpll_id = (enum intel_dpll_id)dig_port->port;
> > > +
> > > + /*
> > > + * FIXME: Works only for BXT.
> > > + * Select the required PLL. This works for platforms where
> > > + * there is no shared DPLL.
> > > + */
> > > + pll = &dev_priv->shared_dplls[dpll_id];
> > > + if (WARN_ON(pll->active_mask)) {
> > > + DRM_ERROR("Shared DPLL already in use.
> > active_mask:%x\n", pll->active_mask);
> > > + return false;
> > > + }
> > > +
> > > + tmp_pll_config = pll->config;
> > > +
> > > + if (!bxt_ddi_dp_set_dpll_hw_state(clock, &pll->config.hw_state)) {
> > > + DRM_ERROR("Could not setup DPLL\n");
> > > + pll->config = tmp_pll_config;
> > > + return false;
> > > + }
> > > +
> > > + /* Enable PLL followed by port */
> > > + pll->funcs.enable(dev_priv, pll);
> > > + intel_ddi_pre_enable_dp(encoder, clock, lane_count, pll);
> > > +
> > > + DRM_DEBUG_KMS("Upfront link train %s: link_clock:%d
> > lanes:%d\n",
> > > + intel_dp->channel_eq_status ? "Passed" : "Failed", clock,
> > lane_count);
> > > +
> > > + /* Disable port followed by PLL for next retry/clean up */
> > > + intel_ddi_post_disable(encoder);
> > > + pll->funcs.disable(dev_priv, pll);
> > > +
> > > + pll->config = tmp_pll_config;
> > > + return intel_dp->channel_eq_status;
> > > +}
> > > +
> > > void intel_ddi_init(struct drm_device *dev, enum port port)
> > > {
> > > struct drm_i915_private *dev_priv = to_i915(dev);
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > b/drivers/gpu/drm/i915/intel_dp.c
> > > index 817897c..394e62d 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -153,12 +153,21 @@ intel_dp_max_link_bw(struct intel_dp
> > *intel_dp)
> > > static u8 intel_dp_max_lane_count(struct intel_dp *intel_dp)
> > > {
> > > struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> > > - u8 source_max, sink_max;
> > > + u8 temp, source_max, sink_max;
> > >
> > > source_max = intel_dig_port->max_lanes;
> > > sink_max = drm_dp_max_lane_count(intel_dp->dpcd);
> > >
> > > - return min(source_max, sink_max);
> > > + temp = min(source_max, sink_max);
> > > +
> > > + /*
> > > + * Limit max lanes w.r.t to the max value found
> > > + * using Upfront link training also.
> > > + */
> > > + if (intel_dp->max_lanes_upfront)
> > > + return min(temp, intel_dp->max_lanes_upfront);
> > > + else
> > > + return temp;
> > > }
> > >
> > > /*
> > > @@ -1380,6 +1389,15 @@ static int intel_dp_common_rates(struct
> > intel_dp *intel_dp,
> > > int source_len, sink_len;
> > >
> > > sink_len = intel_dp_sink_rates(intel_dp, &sink_rates);
> > > +
> > > + /* Cap sink rates w.r.t upfront values */
> > > + if (intel_dp->max_link_rate_upfront) {
> > > + int len = sink_len - 1;
> > > + while (len > 0 && sink_rates[len] > intel_dp-
> > >max_link_rate_upfront)
> > > + len--;
> > > + sink_len = len + 1;
> > > + }
> > > +
> > > source_len = intel_dp_source_rates(intel_dp, &source_rates);
> > >
> > > return intersect_rates(source_rates, source_len,
> > > @@ -4208,6 +4226,114 @@ intel_dp_unset_edid(struct intel_dp *intel_dp)
> > > intel_dp->has_audio = false;
> > > }
> > >
> > > +static int intel_dp_upfront_crtc_disable(struct intel_crtc *crtc,
> > > + struct drm_modeset_acquire_ctx *ctx,
> > > + bool enable)
> > > +{
> > > + int ret;
> > > + struct drm_atomic_state *state;
> > > + struct intel_crtc_state *crtc_state;
> > > + struct drm_device *dev = crtc->base.dev;
> > > + enum pipe pipe = crtc->pipe;
> > > +
> > > + state = drm_atomic_state_alloc(dev);
> > > + if (!state)
> > > + return -ENOMEM;
> > > +
> > > + state->acquire_ctx = ctx;
> > > +
> > > + crtc_state = intel_atomic_get_crtc_state(state, crtc);
> > > + if (IS_ERR(crtc_state)) {
> > > + ret = PTR_ERR(crtc_state);
> > > + drm_atomic_state_free(state);
> > > + return ret;
> > > + }
> > > +
> > > + DRM_DEBUG_KMS("%sabling crtc %c %s upfront link train\n",
> > > + enable ? "En" : "Dis",
> > > + pipe_name(pipe),
> > > + enable ? "after" : "before");
> > > +
> > > + crtc_state->base.active = enable;
> > > + ret = drm_atomic_commit(state);
> > > + if (ret)
> > > + drm_atomic_state_free(state);
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +static bool intel_dp_upfront_link_train(struct intel_dp *intel_dp)
> > > +{
> > > + struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> > > + struct intel_encoder *intel_encoder = &intel_dig_port->base;
> > > + struct drm_device *dev = intel_encoder->base.dev;
> > > + struct drm_i915_private *dev_priv = to_i915(dev);
> > > + struct drm_mode_config *config = &dev->mode_config;
> > > + struct drm_modeset_acquire_ctx ctx;
> > > + struct intel_crtc *intel_crtc;
> > > + struct drm_crtc *crtc = NULL;
> > > + int ret;
> > > + bool done = false;
> > > + uint8_t lane_count, max_lanes = 4;
> > > + int common_rates[DP_MAX_SUPPORTED_RATES] = {};
> > > + int clock, common_len;
> > > +
> > > + common_len = intel_dp_common_rates(intel_dp, common_rates);
> > > + if (WARN_ON(common_len <= 0))
> > > + return true;
> > > +
> > > + drm_modeset_acquire_init(&ctx, 0);
> > > +retry:
> > > + ret = drm_modeset_lock(&config->connection_mutex, &ctx);
> > > + if (ret)
> > > + goto exit_fail;
> > > +
> > > + if (intel_encoder->base.crtc) {
> > > + crtc = intel_encoder->base.crtc;
> > > +
> > > + ret = drm_modeset_lock(&crtc->mutex, &ctx);
> > > + if (ret)
> > > + goto exit_fail;
> > > +
> > > + ret = drm_modeset_lock(&crtc->primary->mutex, &ctx);
> > > + if (ret)
> > > + goto exit_fail;
> > > +
> > > + intel_crtc = to_intel_crtc(crtc);
> > > + ret = intel_dp_upfront_crtc_disable(intel_crtc, &ctx, false);
> >
> > Still seems wrong to just disable things here. And if we can't disable
> > things, then what can we do?
> >
> > I believe there are people working on a proper USB type-C framework,
> > and once that materializes, I'm hoping it could just signal us whenever
> > the cable mode gets changed. I assume the biggest mess for us would
> > be how to detect that we're dealing with a type-C port, so that we'd
> > know when to register for these notifications.
> >
> > Anyway, once there's a proper framework for this stuff, I don't think
> > we'd need any upfront link training snymore. I guess we could use it
> > as a temporary thing, and garbage collect it if/when the proper USB
> > stuff happens?
>
> Sure, I am fine with this as a temporary stuff..
Honestly, I think we should keep the upfront link training support in
place for the long term. There are advantages to knowing the maximum
lane count and link rate that we could successfully train early (vs.
assuming the max that DP supports; we've seen cables and dongles that
limit lane count or link rate to a level lower than what the DP spec
calls out.) We can do a better job of making sure that we will have
enough link bandwidth to support a given mode by knowing the highest
link configuration that we can successfully train at. It also gives
us a more sane default for the DP MST case, rather than assuming the
maximum lane count and link rate (which, again, may not be trainable
in all cases.)
Jim
>
> Thanks,
> Durga
>
> >
> > > + if (ret)
> > > + goto exit_fail;
> > > + }
> > > +
> > > + mutex_lock(&dev_priv->dpll_lock);
> > > +
> > > + for (lane_count = max_lanes; lane_count >= 1 && !done; lane_count
> > >>= 1) {
> > > + for (clock = common_len - 1; clock >= 0 && !done; clock--) {
> > > + done = intel_dp->upfront_link_train(intel_dp,
> > > + common_rates[clock], lane_count);
> > > + if (done) {
> > > + intel_dp->max_lanes_upfront = lane_count;
> > > + intel_dp->max_link_rate_upfront =
> > common_rates[clock];
> > > + break;
> > > + }
> > > + }
> > > + }
> > > +
> > > + mutex_unlock(&dev_priv->dpll_lock);
> > > +
> > > + if (crtc)
> > > + ret = intel_dp_upfront_crtc_disable(intel_crtc, &ctx, true);
> > > +
> > > +exit_fail:
> > > + if (ret == -EDEADLK) {
> > > + drm_modeset_backoff(&ctx);
> > > + goto retry;
> > > + }
> > > + drm_modeset_drop_locks(&ctx);
> > > + drm_modeset_acquire_fini(&ctx);
> > > + return done;
> > > +}
> > > +
> > > static void
> > > intel_dp_long_pulse(struct intel_connector *intel_connector)
> > > {
> > > @@ -4218,7 +4344,7 @@ intel_dp_long_pulse(struct intel_connector
> > *intel_connector)
> > > struct drm_device *dev = connector->dev;
> > > enum drm_connector_status status;
> > > enum intel_display_power_domain power_domain;
> > > - bool ret;
> > > + bool ret, do_upfront_link_train;
> > > u8 sink_irq_vector;
> > >
> > > power_domain =
> > intel_display_port_aux_power_domain(intel_encoder);
> > > @@ -4303,10 +4429,23 @@ intel_dp_long_pulse(struct intel_connector
> > *intel_connector)
> > > DRM_DEBUG_DRIVER("CP or sink specific irq
> > unhandled\n");
> > > }
> > >
> > > + /* Do not do upfront link train, if it is a compliance request */
> > > + do_upfront_link_train = intel_dp->upfront_link_train &&
> > > + !intel_dp->upfront_done &&
> > > + intel_encoder->type == INTEL_OUTPUT_DP
> > &&
> > > + intel_dp->compliance_test_type !=
> > DP_TEST_LINK_TRAINING;
> > > +
> > > + if (do_upfront_link_train) {
> > > + intel_dp->upfront_done =
> > intel_dp_upfront_link_train(intel_dp);
> > > + if (!intel_dp->upfront_done)
> > > + status = connector_status_disconnected;
> > > + }
> > > +
> > > out:
> > > - if ((status != connector_status_connected) &&
> > > - (intel_dp->is_mst == false))
> > > + if (status != connector_status_connected && !intel_dp->is_mst) {
> > > intel_dp_unset_edid(intel_dp);
> > > + intel_dp->upfront_done = false;
> > > + }
> > >
> > > intel_display_power_put(to_i915(dev), power_domain);
> > > return;
> > > @@ -5562,6 +5701,12 @@ intel_dp_init_connector(struct intel_digital_port
> > *intel_dig_port,
> > > if (type == DRM_MODE_CONNECTOR_eDP)
> > > intel_encoder->type = INTEL_OUTPUT_EDP;
> > >
> > > + /* Initialize upfront link training vfunc for DP */
> > > + if (intel_encoder->type != INTEL_OUTPUT_EDP) {
> > > + if (IS_BROXTON(dev))
> > > + intel_dp->upfront_link_train =
> > intel_bxt_upfront_link_train;
> > > + }
> > > +
> > > /* eDP only on port B and/or C on vlv/chv */
> > > if (WARN_ON((IS_VALLEYVIEW(dev) || IS_CHERRYVIEW(dev)) &&
> > > is_edp(intel_dp) && port != PORT_B && port != PORT_C))
> > > diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c
> > b/drivers/gpu/drm/i915/intel_dp_link_training.c
> > > index 60fb39c..e58442a 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp_link_training.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
> > > @@ -232,7 +232,6 @@ static u32 intel_dp_training_pattern(struct intel_dp
> > *intel_dp)
> > > static void
> > > intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
> > > {
> > > - bool channel_eq = false;
> > > int tries, cr_tries;
> > > u32 training_pattern;
> > >
> > > @@ -248,7 +247,7 @@ intel_dp_link_training_channel_equalization(struct
> > intel_dp *intel_dp)
> > >
> > > tries = 0;
> > > cr_tries = 0;
> > > - channel_eq = false;
> > > + intel_dp->channel_eq_status = false;
> > > for (;;) {
> > > uint8_t link_status[DP_LINK_STATUS_SIZE];
> > >
> > > @@ -276,7 +275,7 @@ intel_dp_link_training_channel_equalization(struct
> > intel_dp *intel_dp)
> > >
> > > if (drm_dp_channel_eq_ok(link_status,
> > > intel_dp->lane_count)) {
> > > - channel_eq = true;
> > > + intel_dp->channel_eq_status = true;
> > > break;
> > > }
> > >
> > > @@ -302,7 +301,7 @@ intel_dp_link_training_channel_equalization(struct
> > intel_dp *intel_dp)
> > >
> > > intel_dp_set_idle_link_train(intel_dp);
> > >
> > > - if (channel_eq)
> > > + if (intel_dp->channel_eq_status)
> > > DRM_DEBUG_KMS("Channel EQ done. DP Training
> > successful\n");
> > > }
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h
> > b/drivers/gpu/drm/i915/intel_drv.h
> > > index 16f70d4..88306fc 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -851,6 +851,15 @@ struct intel_dp {
> > > enum hdmi_force_audio force_audio;
> > > bool limited_color_range;
> > > bool color_range_auto;
> > > +
> > > + /* Whether Channel Equalization was achieved during Link training */
> > > + bool channel_eq_status;
> > > +
> > > + /* Upfront link train parameters */
> > > + int max_link_rate_upfront;
> > > + uint8_t max_lanes_upfront;
> > > + bool upfront_done;
> > > +
> > > uint8_t dpcd[DP_RECEIVER_CAP_SIZE];
> > > uint8_t psr_dpcd[EDP_PSR_RECEIVER_CAP_SIZE];
> > > uint8_t downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
> > > @@ -908,6 +917,10 @@ struct intel_dp {
> > > /* This is called before a link training is starterd */
> > > void (*prepare_link_retrain)(struct intel_dp *intel_dp);
> > >
> > > + /* For Upfront link training */
> > > + bool (*upfront_link_train)(struct intel_dp *intel_dp, int clock,
> > > + uint8_t lane_count);
> > > +
> > > /* Displayport compliance testing */
> > > unsigned long compliance_test_type;
> > > unsigned long compliance_test_data;
> > > @@ -1127,6 +1140,8 @@ void intel_ddi_clock_get(struct intel_encoder
> > *encoder,
> > > struct intel_crtc_state *pipe_config);
> > > void intel_ddi_set_vc_payload_alloc(struct drm_crtc *crtc, bool state);
> > > uint32_t ddi_signal_levels(struct intel_dp *intel_dp);
> > > +bool intel_bxt_upfront_link_train(struct intel_dp *intel_dp,
> > > + int clock, uint8_t lane_count);
> > >
> > > /* intel_frontbuffer.c */
> > > void intel_fb_obj_invalidate(struct drm_i915_gem_object *obj,
> > > --
> > > 1.9.1
> >
> > --
> > Ville Syrjälä
> > Intel OTC
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