[Intel-gfx] [PATCHv2 4/4] drm/i915/dp: Enable Upfront link training for typeC DP support on BXT
Ander Conselvan De Oliveira
conselvan2 at gmail.com
Fri Feb 12 16:43:28 UTC 2016
On Mon, 2016-02-01 at 19:27 +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 crtc
> associated with the DP encoder.
> * On Connected boot scenarios: When booted with an LFP and a DP,
> typically, BIOS brings up DP. In these cases, we disable the
> crtc, do upfront link training and then re-enable it back.
> * 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.
>
Please always include a changelog when sending a new version of a patch.
> Signed-off-by: Durgadoss R <durgadoss.r at intel.com>
> ---
> drivers/gpu/drm/i915/intel_ddi.c | 102 +++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/intel_display.c | 38 ++++++++++-
> drivers/gpu/drm/i915/intel_dp.c | 122 ++++++++++++++++++++++++++++++++++
> -
> drivers/gpu/drm/i915/intel_drv.h | 10 +++
> 4 files changed, 270 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c
> b/drivers/gpu/drm/i915/intel_ddi.c
> index 3fb9a03..cc5cad5 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -3217,6 +3217,108 @@ intel_ddi_init_hdmi_connector(struct
> intel_digital_port *intel_dig_port)
> return connector;
> }
>
> +static void intel_ddi_commit_upfront_pll_config(struct intel_dp *intel_dp,
> + struct intel_shared_dpll *pll)
> +{
> + struct intel_shared_dpll_config tmp_config;
> +
> + /*
> + * The shared_dpll_config is computed in intel_get_shared_dpll().
> + * It is committed to 'pll->config' here to be used in
> + * intel_enable/disable_shared_dpll functions. Before committing.
> + * save the existing config, so that once upfront link training is
> + * done, the original value of 'pll->config' can be restored.
> + */
> + tmp_config = pll->config;
> + pll->config = intel_dp->upfront_pll_config;
> + intel_dp->upfront_pll_config = tmp_config;
> +}
> +
> +static struct intel_shared_dpll *intel_ddi_select_upfront_pll_config(
> + struct intel_dp *intel_dp, struct intel_crtc *crtc)
> +{
> + if (!intel_ddi_pll_select(crtc, crtc->config))
> + return NULL;
> +
> + return intel_crtc_to_shared_dpll(crtc);
> +}
> +
> +static void intel_ddi_clear_upfront_pll_config(struct intel_dp *intel_dp,
> + struct intel_shared_dpll *pll)
> +{
> + pll->config = intel_dp->upfront_pll_config;
> +}
> +
The shared pll interface is really getting in the way here. And BXT plls aren't
even shared. We are jumping through hoops to get the pll that matches the given
encoder and to call the code that calculates the dpll_hw_state based on the DP
link rate. I'd like to get that interface fixed but I reckon it will be tricky
to find something that works for all the platforms we support. That's the next
thing on my todo list.
If we have to live with some intermediary solution, I think it would be better
to (almost) completely bypass the shared dpll stuff. First we would need to
split bxt_ddi_pll_sel() so that we would have a function that takes the link
bandwidth and spits out a dpll_hw_state without looking at crtc_state. Then we
would just take the right pll based on dig_port->port, make sure it is not being
used and program it with the hw state we get from that new function.
I wrote a patch to do that split. With it, the PLL enable logic in the upfront
link train logic would look a bit like below. There is some potential for
problems with the state checker, but it should be fine as long as the old dpll
hw state is saved and restored when everything is over.
/* FIXME: this only works for BXT */
dpll_id = (enum intel_dpll_id) dig_port->port;
pll = dev_priv->shared_dplls[dpll_id];
if (WARN_ON(pll->config.crtc_mask) || WARN_ON(pll->active))
goto exit;
bxt_ddi_dp_pll_dividers(crtc->config->port_clock, &clk_div);
if (!bxt_ddi_set_dpll_hw_state(clock, &clk_div,
&pll->config.hw_state)) {
DRM_ERROR("Could not setup DPLL\n");
goto exit;
}
/* Enable PLL followed by port */
pll->enable(dev_priv, pll);
encoder->pre_enable(encoder);
This solution would remove the need for patches 1 and 3.
What do you think?
> +int intel_ddi_upfront_link_train(struct intel_dp *intel_dp,
> + struct intel_crtc *crtc)
> +{
> + struct intel_connector *connector = intel_dp->attached_connector;
> + struct intel_encoder *encoder = connector->encoder;
> + struct intel_shared_dpll *pll = NULL;
> + struct drm_crtc *drm_crtc = NULL;
> + struct intel_crtc_state *tmp_crtc_config;
> + uint8_t link_bw, lane_count;
> +
> + if (!crtc) {
> + drm_crtc = intel_get_unused_crtc(&encoder->base);
> + if (!drm_crtc) {
> + DRM_ERROR("No crtc for upfront link training\n");
> + return -EINVAL;
> + }
> + encoder->base.crtc = drm_crtc;
> + crtc = to_intel_crtc(drm_crtc);
> + }
> +
> + /* Initialize with Max Link rate & lane count supported by panel */
> + link_bw = intel_dp->dpcd[DP_MAX_LINK_RATE];
> + lane_count = drm_dp_max_lane_count(intel_dp->dpcd);
> +
> + /* Save the crtc->config */
> + tmp_crtc_config = crtc->config;
> +
> + DRM_DEBUG_KMS("Using pipe %c\n", pipe_name(crtc->pipe));
> + do {
> + crtc->config->port_clock =
> drm_dp_bw_code_to_link_rate(link_bw);
> + crtc->config->lane_count = lane_count;
> +
> + pll = intel_ddi_select_upfront_pll_config(intel_dp, crtc);
> + if (!pll) {
> + DRM_ERROR("Could not get shared DPLL\n");
> + goto exit;
> + }
> +
> + intel_ddi_commit_upfront_pll_config(intel_dp, pll);
> +
> + /* Enable PLL followed by port */
> + intel_enable_shared_dpll(crtc);
> + encoder->pre_enable(encoder);
> +
> + /* Check if link training passed; if so update DPCD */
> + if (intel_dp->train_set_valid)
> + intel_dp_update_dpcd_params(intel_dp);
> +
> + /* Disable port followed by PLL for next retry/clean up */
> + encoder->post_disable(encoder);
> + intel_disable_shared_dpll(crtc);
> +
> + intel_ddi_clear_upfront_pll_config(intel_dp, pll);
> +
> + } while (!intel_dp->train_set_valid &&
> + intel_dp_get_link_retry_params(intel_dp, &lane_count,
> &link_bw));
> +exit:
> + /* Reset local associations made */
> + if (drm_crtc)
> + encoder->base.crtc = NULL;
> +
> + /* Restore crtc config */
> + crtc->config = tmp_crtc_config;
> +
> + DRM_DEBUG_KMS("Upfront link train %s: lanes:%d bw:%d\n",
> + intel_dp->train_set_valid ? "Passed" : "Failed", lane_count,
> link_bw);
> +
> + return intel_dp->train_set_valid ? 0 : -1;
> +}
> +
> void intel_ddi_init(struct drm_device *dev, enum port port)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
> diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index af50e61..6a650aa 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -4238,16 +4238,45 @@ static void lpt_pch_enable(struct drm_crtc *crtc)
> lpt_enable_pch_transcoder(dev_priv, cpu_transcoder);
> }
>
> +static
> +void intel_get_new_shared_dpll_config(struct drm_i915_private *dev_priv,
> + struct intel_shared_dpll_config
> *shared_dpll)
> +{
> + enum intel_dpll_id i;
> +
> + /* Create a new shared dpll config by duplicating pll->config */
> + for (i = 0; i < dev_priv->num_shared_dpll; i++) {
> + struct intel_shared_dpll *pll = &dev_priv->shared_dplls[i];
> + shared_dpll[i] = pll->config;
> + shared_dpll[i].crtc_mask = 0;
> + }
> +}
> +
> struct intel_shared_dpll *intel_get_shared_dpll(struct intel_crtc *crtc,
> struct intel_crtc_state
> *crtc_state)
> {
> struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
> struct intel_shared_dpll *pll;
> struct intel_shared_dpll_config *shared_dpll;
> + struct intel_shared_dpll_config tmp_config[I915_NUM_PLLS];
> enum intel_dpll_id i;
> int max = dev_priv->num_shared_dpll;
>
> - shared_dpll = intel_atomic_get_shared_dpll_state(crtc_state
> ->base.state);
> + /*
> + * intel_get_shared_dpll needs a shared_dpll[] to store the computed
> + * dpll_config values. For atomic path, it is stored in
> + * intel_atomic_state->shared_dpll[], which is later committed to
> + * dev_priv->shared_dpll[] in atomic commit. For non-atomic path,
> + * (where intel_atomic_state does not exist) the dpll_config values
> + * are stored in 'tmp_config[]' and copied to encoder structures
> + * for later use.
> + */
> + if (crtc_state->base.state) {
> + shared_dpll = intel_atomic_get_shared_dpll_state(crtc_state
> ->base.state);
> + } else {
> + intel_get_new_shared_dpll_config(dev_priv, tmp_config);
> + shared_dpll = tmp_config;
> + }
>
> if (HAS_PCH_IBX(dev_priv->dev)) {
> /* Ironlake PCH has a fixed PLL->PCH pipe mapping. */
> @@ -4277,6 +4306,7 @@ struct intel_shared_dpll *intel_get_shared_dpll(struct
> intel_crtc *crtc,
> pll = &dev_priv->shared_dplls[i];
> DRM_DEBUG_KMS("CRTC:%d using pre-allocated %s\n",
> crtc->base.base.id, pll->name);
> +
> WARN_ON(shared_dpll[i].crtc_mask);
>
> goto found;
> @@ -4325,6 +4355,12 @@ found:
>
> shared_dpll[i].crtc_mask |= 1 << crtc->pipe;
>
> + /*
> + * For DP, this shared dpll config is saved to intel_dp,
> + * and used by upfront link train logic subsequently.
> + */
> + intel_dp_update_shared_dpll_config(crtc_state, shared_dpll[i]);
> +
> return pll;
> }
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index e2bea710..cc7b6f3 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1679,6 +1679,55 @@ void intel_dp_set_link_params(struct intel_dp
> *intel_dp,
> intel_dp->lane_count = pipe_config->lane_count;
> }
>
> +void intel_dp_update_dpcd_params(struct intel_dp *intel_dp)
> +{
> + intel_dp->dpcd[DP_MAX_LANE_COUNT] &= ~DP_MAX_LANE_COUNT_MASK;
> + intel_dp->dpcd[DP_MAX_LANE_COUNT] |=
> + intel_dp->lane_count & DP_MAX_LANE_COUNT_MASK;
> +
> + intel_dp->dpcd[DP_MAX_LINK_RATE] =
> + drm_dp_link_rate_to_bw_code(intel_dp->link_rate);
Maybe it would be good to have an explicit field for actual max lane count and
link rate. That way, reading the DPCD from debugfs will give the actual results
read from the sink instead of an edited value.
> +}
> +
> +bool intel_dp_get_link_retry_params(struct intel_dp *intel_dp,
> + uint8_t *lane_count, uint8_t *link_bw)
> +{
> + /*
> + * As per DP1.3 Spec, retry all link rates for a particular
> + * lane count value, before reducing number of lanes.
> + */
> + if (*link_bw == DP_LINK_BW_5_4) {
> + *link_bw = DP_LINK_BW_2_7;
> + } else if (*link_bw == DP_LINK_BW_2_7) {
> + *link_bw = DP_LINK_BW_1_62;
> + } else if (*lane_count == 4) {
> + *lane_count = 2;
> + *link_bw = intel_dp_max_link_bw(intel_dp);
> + } else if (*lane_count == 2) {
> + *lane_count = 1;
> + *link_bw = intel_dp_max_link_bw(intel_dp);
> + } else {
> + /* Tried all combinations, so exit */
> + return false;
> + }
> +
> + return true;
> +}
> +
> +void intel_dp_update_shared_dpll_config(struct intel_crtc_state *pipe_config,
> + struct intel_shared_dpll_config config)
> +{
> + struct intel_encoder *encoder;
> + struct intel_dp *intel_dp;
> +
> + encoder = intel_ddi_get_crtc_new_encoder(pipe_config);
> + if (!encoder || encoder->type != INTEL_OUTPUT_DISPLAYPORT)
> + return;
> +
> + intel_dp = enc_to_intel_dp(&encoder->base);
> + intel_dp->upfront_pll_config = config;
> +}
> +
> static void intel_dp_prepare(struct intel_encoder *encoder)
> {
> struct drm_device *dev = encoder->base.dev;
> @@ -4601,6 +4650,66 @@ intel_dp_unset_edid(struct intel_dp *intel_dp)
> intel_dp->has_audio = false;
> }
>
> +static bool intel_dp_upfront_link_train(struct drm_connector *connector)
> +{
> + struct intel_dp *intel_dp = intel_attached_dp(connector);
> + 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_crtc *crtc = intel_dig_port->base.base.crtc;
> + struct drm_mode_config *config = &dev->mode_config;
> + struct intel_crtc *intel_crtc = crtc ? to_intel_crtc(crtc) : NULL;
> + struct drm_modeset_acquire_ctx ctx, *old_ctx = NULL;
> + bool need_dpms_on = false;
> + int ret;
> +
> + if (!IS_BROXTON(dev))
> + return true;
> +
> + /*
> + * On hotplug cases, we call _upfront_link_train directly.
> + * In connected boot scenarios (boot with {MIPI/eDP} + DP),
> + * BIOS typically brings up DP. Hence, we disable the crtc
> + * to do _upfront_link_training and then re-enable it back.
> + */
> + if (crtc && crtc->enabled && intel_crtc->active) {
> + old_ctx = crtc->acquire_ctx;
> + drm_modeset_acquire_init(&ctx, 0);
> +retry:
> + ret = drm_modeset_lock(&config->connection_mutex, &ctx);
> + if (ret == -EDEADLK) {
> + drm_modeset_backoff(&ctx);
> + goto retry;
> + }
We need to acquire those locks even if the crtc is disabled, otherwise a modeset
could sneak past and wreak havoc while we are doing the link training and
fiddling with the plls.
> +
> + crtc->acquire_ctx = &ctx;
> + ret = drm_atomic_helper_connector_dpms(connector,
> DRM_MODE_DPMS_OFF);
The crtc->acquire_ctx override seems wrong. One thing that slipped by me when I
looked at the previous version of this patch is that we need to acquire some
locks even if the crtc is already off. So it is probably better to write a
separate function that takes an acquire context and uses atomic to set
crtc_state->active to false and calls drm_atomic_commit().
> + if (ret) {
> + DRM_ERROR("DPMS off failed:%d\n", ret);
> + goto exit_unlock;
> + }
> +
> + need_dpms_on = true;
> + }
> +
> + if (HAS_DDI(dev))
> + ret = intel_ddi_upfront_link_train(intel_dp, intel_crtc);
> + /* Other platforms upfront link train call goes here..*/
> +
> + if (!need_dpms_on)
> + return ret;
> +
> + ret = drm_atomic_helper_connector_dpms(connector, DRM_MODE_DPMS_ON);
> + if (ret)
> + DRM_ERROR("DPMS on failed:%d\n", ret);
> +
> +exit_unlock:
> + drm_modeset_drop_locks(&ctx);
> + drm_modeset_acquire_fini(&ctx);
> + crtc->acquire_ctx = old_ctx;
> + return ret;
The return type of this function is bool. The conversion here will do the wrong
thing, since ret potentially has the return value of functions that return non
-zero on failure.
> +}
> +
> static enum drm_connector_status
> intel_dp_detect(struct drm_connector *connector, bool force)
> {
> @@ -4610,7 +4719,8 @@ intel_dp_detect(struct drm_connector *connector, bool
> force)
> struct drm_device *dev = connector->dev;
> enum drm_connector_status status;
> enum intel_display_power_domain power_domain;
> - bool ret;
> + bool do_upfront_link_train;
> + int ret;
> u8 sink_irq_vector;
>
> DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
> @@ -4684,6 +4794,16 @@ intel_dp_detect(struct drm_connector *connector, bool
> force)
> 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_encoder->type == INTEL_OUTPUT_DISPLAYPORT &&
> + intel_dp->compliance_test_type != DP_TEST_LINK_TRAINING;
> +
> + if (do_upfront_link_train) {
> + ret = intel_dp_upfront_link_train(connector);
> + if (ret)
> + status = connector_status_disconnected;
> + }
So if upfront link training fails because there is no unused crtc we'll say that
the connector is disconnected?
Ander
> out:
> intel_display_power_put(to_i915(dev), power_domain);
> return status;
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h
> index 9fe7c4b..c5ca4ab 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -812,6 +812,9 @@ struct intel_dp {
> unsigned long compliance_test_type;
> unsigned long compliance_test_data;
> bool compliance_test_active;
> +
> + /* Used to store pll config for upfront link training */
> + struct intel_shared_dpll_config upfront_pll_config;
> };
>
> struct intel_digital_port {
> @@ -1031,6 +1034,8 @@ 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);
> +int intel_ddi_upfront_link_train(struct intel_dp *intel_dp,
> + struct intel_crtc *crtc);
>
> /* intel_frontbuffer.c */
> void intel_fb_obj_invalidate(struct drm_i915_gem_object *obj,
> @@ -1239,6 +1244,9 @@ bool intel_dp_init_connector(struct intel_digital_port
> *intel_dig_port,
> struct intel_connector *intel_connector);
> void intel_dp_set_link_params(struct intel_dp *intel_dp,
> const struct intel_crtc_state *pipe_config);
> +void intel_dp_update_dpcd_params(struct intel_dp *intel_dp);
> +bool intel_dp_get_link_retry_params(struct intel_dp *intel_dp,
> + uint8_t *lane_count, uint8_t *link_bw);
> void intel_dp_start_link_train(struct intel_dp *intel_dp);
> void intel_dp_stop_link_train(struct intel_dp *intel_dp);
> void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
> @@ -1246,6 +1254,8 @@ void intel_dp_encoder_destroy(struct drm_encoder
> *encoder);
> int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc);
> bool intel_dp_compute_config(struct intel_encoder *encoder,
> struct intel_crtc_state *pipe_config);
> +void intel_dp_update_shared_dpll_config(struct intel_crtc_state *pipe_config,
> + struct intel_shared_dpll_config config);
> bool intel_dp_is_edp(struct drm_device *dev, enum port port);
> enum irqreturn intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port,
> bool long_hpd);
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