On Fri, Dec 22, 2017 at 08:28:57PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Doing link reatrining from the short pulse handler is problematic since
> that might introduce deadlocks with MST sideband processing. Currently
> we don't retrain MST links from this code, but we want to change that.
> So better to move the entire thing to the hotplug work. We can utilize
> the new encoder->post_hotplug() hook for this.
>
> The only thing we leave in the short pulse handler is the link status
> check. That one still depends on the link parameters stored under
> intel_dp, so no locking around that but races should be mostly harmless
> as the actual retraining code will recheck the link state if we
> end up there by mistake.
>
> Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_ddi.c | 7 +-
> drivers/gpu/drm/i915/intel_dp.c | 213 ++++++++++++++++++++++-----------------
> drivers/gpu/drm/i915/intel_drv.h | 2 +
> 3 files changed, 125 insertions(+), 97 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index 12da7024f01a..7e9964794efe 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -2778,7 +2778,9 @@ static void intel_ddi_post_hotplug(struct intel_encoder *encoder)
> drm_modeset_acquire_init(&ctx, 0);
>
> for (;;) {
> - ret = intel_ddi_hdmi_reset_scrambling(encoder, &ctx);
> + ret = intel_dp_retrain_link(encoder, &ctx);
> + if (!ret)
> + ret = intel_ddi_hdmi_reset_scrambling(encoder, &ctx);
>
> if (ret == -EDEADLK) {
> drm_modeset_backoff(&ctx);
> @@ -2903,8 +2905,7 @@ void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
> drm_encoder_init(&dev_priv->drm, encoder, &intel_ddi_funcs,
> DRM_MODE_ENCODER_TMDS, "DDI %c", port_name(port));
>
> - if (init_hdmi)
> - intel_encoder->post_hotplug = intel_ddi_post_hotplug;
> + intel_encoder->post_hotplug = intel_ddi_post_hotplug;
Same goes here for the name, may be call it intel_ddi_hotplug_post_detect()?
> intel_encoder->compute_output_type = intel_ddi_compute_output_type;
> intel_encoder->compute_config = intel_ddi_compute_config;
> intel_encoder->enable = intel_enable_ddi;
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 35c5299feab6..72234c5dc15b 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4251,74 +4251,137 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
> return -EINVAL;
> }
>
> -static void
> -intel_dp_retrain_link(struct intel_dp *intel_dp)
> +static bool
> +intel_dp_needs_link_retrain(struct intel_dp *intel_dp)
> {
> - struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;
> - struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> - struct intel_crtc *crtc = to_intel_crtc(encoder->base.crtc);
> -
> - /* Suppress underruns caused by re-training */
> - intel_set_cpu_fifo_underrun_reporting(dev_priv, crtc->pipe, false);
> - if (crtc->config->has_pch_encoder)
> - intel_set_pch_fifo_underrun_reporting(dev_priv,
> - intel_crtc_pch_transcoder(crtc), false);
> -
> - intel_dp_start_link_train(intel_dp);
> - intel_dp_stop_link_train(intel_dp);
> -
> - /* Keep underrun reporting disabled until things are stable */
> - intel_wait_for_vblank(dev_priv, crtc->pipe);
> -
> - intel_set_cpu_fifo_underrun_reporting(dev_priv, crtc->pipe, true);
> - if (crtc->config->has_pch_encoder)
> - intel_set_pch_fifo_underrun_reporting(dev_priv,
> - intel_crtc_pch_transcoder(crtc), true);
> -}
> -
> -static void
> -intel_dp_check_link_status(struct intel_dp *intel_dp)
> -{
> - struct drm_i915_private *dev_priv = to_i915(intel_dp_to_dev(intel_dp));
> - struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
> - struct drm_connector_state *conn_state =
> - intel_dp->attached_connector->base.state;
> u8 link_status[DP_LINK_STATUS_SIZE];
>
> - WARN_ON(!drm_modeset_is_locked(&dev_priv->drm.mode_config.connection_mutex));
> -
> if (!intel_dp_get_link_status(intel_dp, link_status)) {
> DRM_ERROR("Failed to get link status\n");
> - return;
> + return false;
> }
>
> - if (!conn_state->crtc)
> - return;
> -
> - WARN_ON(!drm_modeset_is_locked(&conn_state->crtc->mutex));
> -
> - if (!conn_state->crtc->state->active)
> - return;
> -
> - if (conn_state->commit &&
> - !try_wait_for_completion(&conn_state->commit->hw_done))
> - return;
> -
> /*
> * Validate the cached values of intel_dp->link_rate and
> * intel_dp->lane_count before attempting to retrain.
> */
> if (!intel_dp_link_params_valid(intel_dp, intel_dp->link_rate,
> intel_dp->lane_count))
> - return;
> + return false;
>
> /* Retrain if Channel EQ or CR not ok */
> - if (!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count)) {
> - DRM_DEBUG_KMS("%s: channel EQ not ok, retraining\n",
> - intel_encoder->base.name);
> + return !drm_dp_channel_eq_ok(link_status, intel_dp->lane_count);
> +}
>
> - intel_dp_retrain_link(intel_dp);
> +/*
> + * If display is now connected check links status,
> + * there has been known issues of link loss triggering
> + * long pulse.
> + *
> + * Some sinks (eg. ASUS PB287Q) seem to perform some
> + * weird HPD ping pong during modesets. So we can apparently
> + * end up with HPD going low during a modeset, and then
> + * going back up soon after. And once that happens we must
> + * retrain the link to get a picture. That's in case no
> + * userspace component reacted to intermittent HPD dip.
> + */
> +int intel_dp_retrain_link(struct intel_encoder *encoder,
> + struct drm_modeset_acquire_ctx *ctx)
> +{
> + struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> + struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> + struct intel_connector *connector = intel_dp->attached_connector;
> + struct drm_connector_state *conn_state;
> + struct intel_crtc_state *crtc_state;
> + struct intel_crtc *crtc;
> + int ret;
> +
> + /* FIXME handle the MST connectors as well */
> +
> + if (!connector || connector->base.status != connector_status_connected)
> + return 0;
> +
> + ret = drm_modeset_lock(&dev_priv->drm.mode_config.connection_mutex, ctx);
> + if (ret)
> + return ret;
> +
> + conn_state = connector->base.state;
> +
> + crtc = to_intel_crtc(conn_state->crtc);
> + if (!crtc)
> + return 0;
> +
> + ret = drm_modeset_lock(&crtc->base.mutex, ctx);
> + if (ret)
> + return ret;
> +
> + crtc_state = to_intel_crtc_state(crtc->base.state);
> +
> + WARN_ON(!intel_crtc_has_dp_encoder(crtc_state));
> +
> + if (!crtc_state->base.active)
> + return 0;
> +
> + if (conn_state->commit &&
> + !try_wait_for_completion(&conn_state->commit->hw_done))
> + return 0;
> +
> + if (!intel_dp_needs_link_retrain(intel_dp))
> + return 0;
> +
> + /* Suppress underruns caused by re-training */
> + intel_set_cpu_fifo_underrun_reporting(dev_priv, crtc->pipe, false);
> + if (crtc->config->has_pch_encoder)
> + intel_set_pch_fifo_underrun_reporting(dev_priv,
> + intel_crtc_pch_transcoder(crtc), false);
> +
> + intel_dp_start_link_train(intel_dp);
> + intel_dp_stop_link_train(intel_dp);
> +
> + /* Keep underrun reporting disabled until things are stable */
> + intel_wait_for_vblank(dev_priv, crtc->pipe);
> +
> + intel_set_cpu_fifo_underrun_reporting(dev_priv, crtc->pipe, true);
> + if (crtc->config->has_pch_encoder)
> + intel_set_pch_fifo_underrun_reporting(dev_priv,
> + intel_crtc_pch_transcoder(crtc), true);
> +
> + return 0;
> +}
> +
> +/*
> + * If display is now connected check links status,
> + * there has been known issues of link loss triggering
> + * long pulse.
> + *
> + * Some sinks (eg. ASUS PB287Q) seem to perform some
> + * weird HPD ping pong during modesets. So we can apparently
> + * end up with HPD going low during a modeset, and then
> + * going back up soon after. And once that happens we must
> + * retrain the link to get a picture. That's in case no
> + * userspace component reacted to intermittent HPD dip.
> + */
> +static void intel_dp_post_hotplug(struct intel_encoder *encoder)
> +{
> + struct drm_modeset_acquire_ctx ctx;
> + int ret;
> +
> + drm_modeset_acquire_init(&ctx, 0);
> +
> + for (;;) {
> + ret = intel_dp_retrain_link(encoder, &ctx);
> +
> + if (ret == -EDEADLK) {
> + drm_modeset_backoff(&ctx);
> + continue;
> + }
> +
> + break;
> }
> +
> + drm_modeset_drop_locks(&ctx);
> + drm_modeset_acquire_fini(&ctx);
> + WARN(ret, "Acquiring modeset locks failed with %i\n", ret);
> }
>
I like that now intel_dp_long_pulse() and intel_dp_short_pulse() dont need to call
link retraining separately. This post_hotplug will take care of retraining after long and short
pulse.
Acked-by: Manasi Navare <manasi.d.navare@xxxxxxxxx>
Manasi
> /*
> @@ -4376,7 +4439,9 @@ intel_dp_short_pulse(struct intel_dp *intel_dp)
> DRM_DEBUG_DRIVER("CP or sink specific irq unhandled\n");
> }
>
> - intel_dp_check_link_status(intel_dp);
> + /* defer to the hotplug work for link retraining if needed */
> + if (intel_dp_needs_link_retrain(intel_dp))
> + return false;
>
> if (intel_dp->compliance.test_type == DP_TEST_LINK_TRAINING) {
> DRM_DEBUG_KMS("Link Training Compliance Test requested\n");
> @@ -4761,20 +4826,6 @@ intel_dp_long_pulse(struct intel_connector *connector)
> */
> status = connector_status_disconnected;
> goto out;
> - } else {
> - /*
> - * If display is now connected check links status,
> - * there has been known issues of link loss triggerring
> - * long pulse.
> - *
> - * Some sinks (eg. ASUS PB287Q) seem to perform some
> - * weird HPD ping pong during modesets. So we can apparently
> - * end up with HPD going low during a modeset, and then
> - * going back up soon after. And once that happens we must
> - * retrain the link to get a picture. That's in case no
> - * userspace component reacted to intermittent HPD dip.
> - */
> - intel_dp_check_link_status(intel_dp);
> }
>
> /*
> @@ -5119,37 +5170,10 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
> }
>
> if (!intel_dp->is_mst) {
> - struct drm_modeset_acquire_ctx ctx;
> - struct drm_connector *connector = &intel_dp->attached_connector->base;
> - struct drm_crtc *crtc;
> - int iret;
> - bool handled = false;
> -
> - drm_modeset_acquire_init(&ctx, 0);
> -retry:
> - iret = drm_modeset_lock(&dev_priv->drm.mode_config.connection_mutex, &ctx);
> - if (iret)
> - goto err;
> -
> - crtc = connector->state->crtc;
> - if (crtc) {
> - iret = drm_modeset_lock(&crtc->mutex, &ctx);
> - if (iret)
> - goto err;
> - }
> + bool handled;
>
> handled = intel_dp_short_pulse(intel_dp);
>
> -err:
> - if (iret == -EDEADLK) {
> - drm_modeset_backoff(&ctx);
> - goto retry;
> - }
> -
> - drm_modeset_drop_locks(&ctx);
> - drm_modeset_acquire_fini(&ctx);
> - WARN(iret, "Acquiring modeset locks failed with %i\n", iret);
> -
> if (!handled) {
> intel_dp->detect_done = false;
> goto put_power;
> @@ -6170,6 +6194,7 @@ bool intel_dp_init(struct drm_i915_private *dev_priv,
> "DP %c", port_name(port)))
> goto err_encoder_init;
>
> + intel_encoder->post_hotplug = intel_dp_post_hotplug;
> intel_encoder->compute_config = intel_dp_compute_config;
> intel_encoder->get_hw_state = intel_dp_get_hw_state;
> intel_encoder->get_config = intel_dp_get_config;
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 4a7e603ccc38..f95ac56784e6 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1530,6 +1530,8 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> int link_rate, uint8_t lane_count);
> void intel_dp_start_link_train(struct intel_dp *intel_dp);
> void intel_dp_stop_link_train(struct intel_dp *intel_dp);
> +int intel_dp_retrain_link(struct intel_encoder *encoder,
> + struct drm_modeset_acquire_ctx *ctx);
> void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
> void intel_dp_encoder_reset(struct drm_encoder *encoder);
> void intel_dp_encoder_suspend(struct intel_encoder *intel_encoder);
> --
> 2.13.6
>
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