[Intel-gfx] [PATCH 11/14] drm/i915: Fallback to lower link rate and lane count during link training
David Weinehall
david.weinehall at linux.intel.com
Fri Sep 2 12:49:02 UTC 2016
On Thu, Sep 01, 2016 at 03:08:16PM -0700, Manasi Navare wrote:
> According to the DisplayPort Spec, in case of Clock Recovery failure
> the link training sequence should fall back to the lower link rate
> followed by lower lane count until CR succeeds.
> On CR success, the sequence proceeds with Channel EQ.
> In case of Channel EQ failures, it should fallback to
> lower link rate and lane count and start the CR phase again.
>
> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> ---
> drivers/gpu/drm/i915/intel_ddi.c | 109 +++++++++++++++++++++++---
> drivers/gpu/drm/i915/intel_dp_link_training.c | 12 ++-
> drivers/gpu/drm/i915/intel_drv.h | 4 +-
> 3 files changed, 110 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index 67a6a0b..78d6687 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -1634,29 +1634,50 @@ void intel_ddi_clk_select(struct intel_encoder *encoder,
> }
> }
>
> -static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
> +static void intel_ddi_pre_enable_edp(struct intel_encoder *encoder,
> int link_rate, uint32_t lane_count,
> - struct intel_shared_dpll *pll,
> - bool link_mst)
> + struct intel_shared_dpll *pll)
> {
> struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> enum port port = intel_ddi_get_encoder_port(encoder);
>
> intel_dp_set_link_params(intel_dp, link_rate, lane_count,
> - link_mst);
> - if (encoder->type == INTEL_OUTPUT_EDP)
> - intel_edp_panel_on(intel_dp);
> + false);
> +
> + intel_edp_panel_on(intel_dp);
>
> intel_ddi_clk_select(encoder, pll);
> intel_prepare_dp_ddi_buffers(encoder);
> intel_ddi_init_dp_buf_reg(encoder);
> intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> intel_dp_start_link_train(intel_dp);
> - if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
> + if (port != PORT_A || INTEL_INFO(dev_priv)->gen >= 9)
> intel_dp_stop_link_train(intel_dp);
> }
>
> +static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
> + int link_rate, uint32_t lane_count,
> + struct intel_shared_dpll *pll,
> + bool link_mst)
> +{
> + struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> + struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> + struct intel_shared_dpll_config tmp_pll_config;
> +
> + /* Disable the PLL and obtain the PLL for Link Training
> + * that starts with highest link rate and lane count.
> + */
> + tmp_pll_config = pll->config;
> + pll->funcs.disable(dev_priv, pll);
> + pll->config.crtc_mask = 0;
> +
> + /* If Link Training fails, send a uevent to generate a hotplug */
> + if (!(intel_ddi_link_train(intel_dp, link_rate, lane_count, link_mst)))
> + drm_kms_helper_hotplug_event(encoder->base.dev);
> + pll->config = tmp_pll_config;
> +}
> +
> static void intel_ddi_pre_enable_hdmi(struct intel_encoder *encoder,
> bool has_hdmi_sink,
> struct drm_display_mode *adjusted_mode,
> @@ -1690,20 +1711,26 @@ static void intel_ddi_pre_enable(struct intel_encoder *intel_encoder,
> struct intel_crtc *crtc = to_intel_crtc(encoder->crtc);
> int type = intel_encoder->type;
>
> - if (type == INTEL_OUTPUT_DP || type == INTEL_OUTPUT_EDP) {
> + if (type == INTEL_OUTPUT_EDP)
> + intel_ddi_pre_enable_edp(intel_encoder,
> + crtc->config->port_clock,
> + crtc->config->lane_count,
> + crtc->config->shared_dpll);
> +
> + if (type == INTEL_OUTPUT_DP)
> intel_ddi_pre_enable_dp(intel_encoder,
> crtc->config->port_clock,
> crtc->config->lane_count,
> crtc->config->shared_dpll,
> intel_crtc_has_type(crtc->config,
> INTEL_OUTPUT_DP_MST));
> - }
> - if (type == INTEL_OUTPUT_HDMI) {
> +
> + if (type == INTEL_OUTPUT_HDMI)
> intel_ddi_pre_enable_hdmi(intel_encoder,
> crtc->config->has_hdmi_sink,
> &crtc->config->base.adjusted_mode,
> crtc->config->shared_dpll);
> - }
> +
> }
>
> static void intel_ddi_post_disable(struct intel_encoder *intel_encoder,
> @@ -2431,6 +2458,66 @@ intel_ddi_get_link_dpll(struct intel_dp *intel_dp, int clock)
> return pll;
> }
>
> +bool
> +intel_ddi_link_train(struct intel_dp *intel_dp, int max_link_rate,
> + uint8_t max_lane_count, bool link_mst)
> +{
> + 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;
> + int link_rate;
> + uint8_t lane_count;
> + bool link_rate_not_found = true;
> + bool ret = false;
> +
> + for (lane_count = max_lane_count; lane_count > 0; lane_count >>= 1) {
> +
> + link_rate = max_link_rate;
> + while (link_rate_not_found) {
> + pll = intel_ddi_get_link_dpll(intel_dp, link_rate);
> + if (pll == NULL) {
> + DRM_ERROR("Could not find DPLL for link "
> + "training.\n");
> + return false;
> + }
> + tmp_pll_config = pll->config;
> + pll->funcs.enable(dev_priv, pll);
> +
> + intel_dp_set_link_params(intel_dp, link_rate,
> + lane_count, link_mst);
> +
> + intel_ddi_clk_select(encoder, pll);
> + intel_prepare_dp_ddi_buffers(encoder);
> + intel_ddi_init_dp_buf_reg(encoder);
Do you really need to run these two for every link rate?
> + intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> + ret = intel_dp_start_link_train(intel_dp);
> + if (ret)
> + break;
Where do you stop link training on failure? Perhaps:
ret = intel_dp_start_link_train(intel_dp);
intel_dp_stop_link_train(intel_dp);
if (ret)
break;
and remove the stop on the success path?
> +
> + /* Disable port followed by PLL for next retry/clean up */
> + intel_ddi_post_disable(encoder, NULL, NULL);
> + pll->funcs.disable(dev_priv, pll);
> + if (link_rate == 540000)
> + link_rate = 270000;
> + else if (link_rate == 270000)
> + link_rate = 162000;
> + else
> + link_rate_not_found = false;
> + }
> + if (ret) {
> + DRM_DEBUG_KMS("Link Training successful\n");
> + intel_dp_stop_link_train(intel_dp);
> + break;
> + }
> + }
> + if (!lane_count)
> + DRM_ERROR("Link Training Failed\n");
> +
> + return ret;
> +}
> +
> 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_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c
> index 07f0159..0df49e8 100644
> --- a/drivers/gpu/drm/i915/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
> @@ -309,9 +309,15 @@ void intel_dp_stop_link_train(struct intel_dp *intel_dp)
> DP_TRAINING_PATTERN_DISABLE);
> }
>
> -void
> +bool
> intel_dp_start_link_train(struct intel_dp *intel_dp)
> {
> - intel_dp_link_training_clock_recovery(intel_dp);
> - intel_dp_link_training_channel_equalization(intel_dp);
> + bool ret;
> +
> + if (intel_dp_link_training_clock_recovery(intel_dp)) {
> + ret = intel_dp_link_training_channel_equalization(intel_dp);
> + if (ret)
> + return true;
> + }
> + return false;
> }
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index e5bc976..342a2d5 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1160,6 +1160,8 @@ 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_ddi_link_train(struct intel_dp *intel_dp, int max_link_rate,
> + uint8_t max_lane_count, bool link_mst);
> struct intel_shared_dpll *intel_ddi_get_link_dpll(struct intel_dp *intel_dp,
> int clock);
> unsigned int intel_fb_align_height(struct drm_device *dev,
> @@ -1381,7 +1383,7 @@ bool intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
> void intel_dp_set_link_params(struct intel_dp *intel_dp,
> int link_rate, uint8_t lane_count,
> bool link_mst);
> -void intel_dp_start_link_train(struct intel_dp *intel_dp);
> +bool 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);
> void intel_dp_encoder_reset(struct drm_encoder *encoder);
> --
> 1.9.1
>
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