[Intel-gfx] [PATCH v2 14/14] drm/i915/dp/mst: Add support for upfront link training for DP MST
Mika Kahola
mika.kahola at intel.com
Wed Sep 7 10:53:31 UTC 2016
On Tue, 2016-09-06 at 17:13 -0700, Manasi Navare wrote:
> From: Jim Bride <jim.bride at linux.intel.com>
>
> Add upfront link training to intel_dp_mst_mode_valid() so that we
> know
> topology constraints before we validate the legality of modes to be
> checked.
> Call the function that loops through the link rates and lane counts
> starting from highest supported link rate and lane count for training
> the link in compliance with DP spec
>
> v2:
> * Rebased on new revision of link training patch (Manasi Navare)
>
> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> Signed-off-by: Jim Bride <jim.bride at linux.intel.com>
> ---
> drivers/gpu/drm/i915/intel_dp.c | 9 ++---
> drivers/gpu/drm/i915/intel_dp_mst.c | 74
> +++++++++++++++++++++++++++----------
> drivers/gpu/drm/i915/intel_drv.h | 3 ++
> 3 files changed, 61 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c
> b/drivers/gpu/drm/i915/intel_dp.c
> index 7794180..0c7674f 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -131,7 +131,7 @@ static void vlv_steal_power_sequencer(struct
> drm_device *dev,
> enum pipe pipe);
> static void intel_dp_unset_edid(struct intel_dp *intel_dp);
>
> -static int
> +int
> intel_dp_max_link_bw(struct intel_dp *intel_dp)
> {
> int max_link_bw = intel_dp->dpcd[DP_MAX_LINK_RATE];
> @@ -150,7 +150,7 @@ intel_dp_max_link_bw(struct intel_dp *intel_dp)
> return max_link_bw;
> }
>
> -static u8 intel_dp_max_lane_count(struct intel_dp *intel_dp)
> +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 temp, source_max, sink_max;
> @@ -312,8 +312,7 @@ static int intersect_rates(const int
> *source_rates, int source_len,
> return k;
> }
>
> -static int intel_dp_common_rates(struct intel_dp *intel_dp,
> - int *common_rates)
> +int intel_dp_common_rates(struct intel_dp *intel_dp, int
> *common_rates)
> {
> const int *source_rates, *sink_rates;
> int source_len, sink_len;
> @@ -336,7 +335,7 @@ static int intel_dp_common_rates(struct intel_dp
> *intel_dp,
> common_rates);
> }
>
> -static bool intel_dp_upfront_link_train(struct intel_dp *intel_dp)
> +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;
> diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c
> b/drivers/gpu/drm/i915/intel_dp_mst.c
> index 54a9d76..98d45a4 100644
> --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> @@ -41,21 +41,30 @@ static bool intel_dp_mst_compute_config(struct
> intel_encoder *encoder,
> int bpp;
> int lane_count, slots;
> const struct drm_display_mode *adjusted_mode = &pipe_config-
> >base.adjusted_mode;
> - int mst_pbn;
> + int mst_pbn, common_len;
> + int common_rates[DP_MAX_SUPPORTED_RATES] = {};
>
> pipe_config->dp_encoder_is_mst = true;
> pipe_config->has_pch_encoder = false;
> - bpp = 24;
> +
> /*
> - * for MST we always configure max link bw - the spec
> doesn't
> - * seem to suggest we should do otherwise.
> + * For MST we always configure for the maximum trainable
> link bw -
> + * the spec doesn't seem to suggest we should do
> otherwise. The
> + * calls to intel_dp_max_lane_count() and
> intel_dp_common_rates()
> + * both take successful upfront link training into account,
> and
> + * return the DisplayPort max supported values in the event
> that
> + * upfront link training was not done.
> */
> - lane_count = drm_dp_max_lane_count(intel_dp->dpcd);
> + lane_count = intel_dp_max_lane_count(intel_dp);
>
> pipe_config->lane_count = lane_count;
>
> - pipe_config->pipe_bpp = 24;
> - pipe_config->port_clock = intel_dp_max_link_rate(intel_dp);
> + pipe_config->pipe_bpp = bpp = 24;
> + common_len = intel_dp_common_rates(intel_dp, common_rates);
> + pipe_config->port_clock = common_rates[common_len - 1];
> +
> + DRM_DEBUG_KMS("DP MST link configured for %d lanes @ %d.\n",
> + pipe_config->lane_count, pipe_config-
> >port_clock);
>
> state = pipe_config->base.state;
>
> @@ -137,6 +146,8 @@ static void intel_mst_pre_enable_dp(struct
> intel_encoder *encoder,
> enum port port = intel_dig_port->port;
> struct intel_connector *connector =
> to_intel_connector(conn_state->connector);
> + struct intel_shared_dpll *pll = pipe_config->shared_dpll;
> + struct intel_shared_dpll_config tmp_pll_config;
> int ret;
> uint32_t temp;
> int slots;
> @@ -150,21 +161,23 @@ static void intel_mst_pre_enable_dp(struct
> intel_encoder *encoder,
> DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
>
> if (intel_dp->active_mst_links == 0) {
> - intel_ddi_clk_select(&intel_dig_port->base,
> - pipe_config->shared_dpll);
> -
> - intel_prepare_dp_ddi_buffers(&intel_dig_port->base);
> - intel_dp_set_link_params(intel_dp,
> - pipe_config->port_clock,
> - pipe_config->lane_count,
> - true);
> -
> - intel_ddi_init_dp_buf_reg(&intel_dig_port->base);
>
> - intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> + /* Disable the PLL since we need to acquire the PLL
> + * based on the link rate in the link training
> sequence
> + */
> + 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, pipe_config-
> >port_clock,
> + pipe_config->lane_count,
> true,
> + false)))
> + drm_kms_helper_hotplug_event(encoder-
> >base.dev);
> + pll->config = tmp_pll_config;
>
> - intel_dp_start_link_train(intel_dp);
> - intel_dp_stop_link_train(intel_dp);
> }
>
> ret = drm_dp_mst_allocate_vcpi(&intel_dp->mst_mgr,
> @@ -336,6 +349,27 @@ intel_dp_mst_mode_valid(struct drm_connector
> *connector,
> struct drm_display_mode *mode)
> {
> int max_dotclk = to_i915(connector->dev)->max_dotclk_freq;
> + struct intel_connector *intel_connector =
> to_intel_connector(connector);
> + struct intel_dp *intel_dp = intel_connector->mst_port;
> +
> + if (intel_dp->upfront_link_train && !intel_dp->upfront_done)
> {
> + bool do_upfront_link_train;
> +
> + do_upfront_link_train = 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) {
> + DRM_DEBUG_KMS("MST upfront trained
> at "
> + "%d lanes @ %d.",
> + intel_dp-
> >max_lanes_upfront,
> + intel_dp-
> >max_link_rate_upfront);
> + } else
> + DRM_DEBUG_KMS("MST upfront link
> training "
> + "failed.");
Link training has failed and we have a blank screen. Should we throw an
error here? Maybe
return MODE_ERROR;
> + }
> + }
>
> /* TODO - validate mode against available PBN for link */
> if (mode->clock < 10000)
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h
> index a2bbf68..34af3e8 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1416,6 +1416,7 @@ void intel_edp_panel_off(struct intel_dp
> *intel_dp);
> void intel_dp_add_properties(struct intel_dp *intel_dp, struct
> drm_connector *connector);
> void intel_dp_mst_suspend(struct drm_device *dev);
> void intel_dp_mst_resume(struct drm_device *dev);
> +u8 intel_dp_max_lane_count(struct intel_dp *intel_dp);
> int intel_dp_max_link_rate(struct intel_dp *intel_dp);
> int intel_dp_link_rate_index(struct intel_dp *intel_dp, int
> *common_rates,
> int link_rate);
> @@ -1448,6 +1449,8 @@ intel_dp_pre_emphasis_max(struct intel_dp
> *intel_dp, uint8_t voltage_swing);
> void intel_dp_compute_rate(struct intel_dp *intel_dp, int
> port_clock,
> uint8_t *link_bw, uint8_t *rate_select);
> bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp);
> +int intel_dp_common_rates(struct intel_dp *intel_dp, int
> *common_rates);
> +bool intel_dp_upfront_link_train(struct intel_dp *intel_dp);
> bool
> intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t
> link_status[DP_LINK_STATUS_SIZE]);
>
--
Mika Kahola - Intel OTC
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