[Intel-gfx] [PATCH] drm/i915: Expand documentation for gen12 DP pre-enable sequence
Souza, Jose
jose.souza at intel.com
Thu Nov 7 20:16:13 UTC 2019
On Thu, 2019-11-07 at 09:45 -0800, Matt Roper wrote:
> Rather than just specifying the bullet numbers from the bspec (e.g.,
> "4.b") actually include the description of what the bspec wants us to
> do. Steps can be renumbered or moved so including the description
> will
> help us match the code up to the spec. Plus if we add support for
> new
> platforms, some of the steps may be added/removed so more descriptive
> comments will be useful for ensuring all of the bspec requirements
> are
> met.
>
> Cc: José Roberto de Souza <jose.souza at intel.com>
> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_ddi.c | 92 ++++++++++++++++++--
> ----
> 1 file changed, 72 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c
> b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 398c6f054a6e..ad39cd608011 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -3438,48 +3438,86 @@ static void tgl_ddi_pre_enable_dp(struct
> intel_encoder *encoder,
> intel_dp->regs.dp_tp_ctl = TGL_DP_TP_CTL(transcoder);
> intel_dp->regs.dp_tp_status = TGL_DP_TP_STATUS(transcoder);
>
> - /* 1.a got on intel_atomic_commit_tail() */
> + /*
> + * 1. Enable Power Wells
> + *
> + * This was handled at the beginning of
> intel_atomic_commit_tail(),
> + * before we called down into this function.
> + */
>
> - /* 2. */
> + /* 2. Enable Panel Power if PPS is required */
> intel_edp_panel_on(intel_dp);
>
> /*
> - * 1.b, 3. and 4.a is done before tgl_ddi_pre_enable_dp() by:
> - * haswell_crtc_enable()->intel_encoders_pre_pll_enable() and
> - * haswell_crtc_enable()->intel_enable_shared_dpll()
> + * 3. For non-TBT Type-C ports, set FIA lane count
> + * (DFLEXDPSP.DPX4TXLATC)
> + *
> + * This was done before tgl_ddi_pre_enable_dp by
> + * haswell_crtc_enable()->intel_encoders_pre_pll_enable().
> */
>
> - /* 4.b */
> + /*
> + * 4. Enable the port PLL.
> + *
> + * The PLL enabling itself was already done before this
> function by
> + * haswell_crtc_enable()->intel_enable_shared_dpll(). We need
> only
> + * configure the PLL to port mapping here.
> + */
> intel_ddi_clk_select(encoder, crtc_state);
>
> - /* 5. */
> + /* 5. If IO power is controlled through PWR_WELL_CTL, Enable IO
> Power */
> if (!intel_phy_is_tc(dev_priv, phy) ||
> dig_port->tc_mode != TC_PORT_TBT_ALT)
> intel_display_power_get(dev_priv,
> dig_port->ddi_io_power_domain);
>
> - /* 6. */
> + /* 6. Program DP_MODE */
> icl_program_mg_dp_mode(dig_port, crtc_state);
>
> /*
> - * 7.a - single stream or multi-stream master transcoder:
> Configure
> - * Transcoder Clock Select. For additional MST streams this
> will be done
> - * by intel_mst_pre_enable_dp() after programming VC Payload ID
> through
> - * AUX.
> + * 7. The rest of the below are substeps under the bspec's
> "Enable and
> + * Train Display Port" step. Note that steps that are specific
> to
> + * MST will be handled by intel_mst_pre_enable_dp()
> before/after it
> + * calls into this function. Also intel_mst_pre_enable_dp()
> only calls
> + * us when active_mst_links==0, so any steps designated for
> "single
> + * stream or multi-stream master transcoder" can just be
> performed
> + * unconditionally here.
> + */
> +
> + /*
> + * 7a. Configure Transcoder Clock Select to direct the Port
> clock to the
> + * Transcoder.
Before push, please fix:
s/7a/7.a
s/7b/7.b
...
To keep consistent with the steps above
Other than that:
Reviewed-by: José Roberto de Souza <jose.souza at intel.com>
> */
> intel_ddi_enable_pipe_clock(crtc_state);
>
> - /* 7.b */
> + /*
> + * 7b. Configure TRANS_DDI_FUNC_CTL DDI Select, DDI Mode Select
> & MST
> + * Transport Select
> + */
> intel_ddi_config_transcoder_func(crtc_state);
>
> - /* 7.d */
> + /*
> + * 7c. Configure & enable DP_TP_CTL with link training pattern
> 1
> + * selected
> + *
> + * This will be handled by the intel_dp_start_link_train()
> farther
> + * down this function.
> + */
> +
> + /*
> + * 7d. Type C with DP alternate or fixed/legacy/static
> connection -
> + * Disable PHY clock gating per Type-C DDI Buffer page
> + */
> icl_phy_set_clock_gating(dig_port, false);
>
> - /* 7.e */
> + /* 7e. Configure voltage swing and related IO settings */
> tgl_ddi_vswing_sequence(encoder, crtc_state->port_clock, level,
> encoder->type);
>
> - /* 7.f */
> + /*
> + * 7f. Combo PHY: Configure PORT_CL_DW10 Static Power Down to
> power up
> + * the used lanes of the DDI.
> + */
> if (intel_phy_is_combo(dev_priv, phy)) {
> bool lane_reversal =
> dig_port->saved_port_bits &
> DDI_BUF_PORT_REVERSAL;
> @@ -3489,7 +3527,14 @@ static void tgl_ddi_pre_enable_dp(struct
> intel_encoder *encoder,
> lane_reversal);
> }
>
> - /* 7.g */
> + /*
> + * 7g. Configure and enable DDI_BUF_CTL
> + * 7h. Wait for DDI_BUF_CTL DDI Idle Status = 0b (Not Idle),
> timeout
> + * after 500 us.
> + *
> + * We only configure what the register value will be
> here. Actual
> + * enabling happens during link training farther down.
> + */
> intel_ddi_init_dp_buf_reg(encoder);
>
> if (!is_mst)
> @@ -3502,10 +3547,17 @@ static void tgl_ddi_pre_enable_dp(struct
> intel_encoder *encoder,
> * training
> */
> intel_dp_sink_set_fec_ready(intel_dp, crtc_state);
> - /* 7.c, 7.h, 7.i, 7.j */
> +
> + /*
> + * 7i. Follow DisplayPort specification training sequence (see
> notes for
> + * failure handling)
> + * 7j. If DisplayPort multi-stream - Set DP_TP_CTL link
> training to Idle
> + * Pattern, wait for 5 idle patterns (DP_TP_STATUS
> Min_Idles_Sent)
> + * (timeout after 800 us)
> + */
> intel_dp_start_link_train(intel_dp);
>
> - /* 7.k */
> + /* 7k. Set DP_TP_CTL link training to Normal */
> if (!is_trans_port_sync_mode(crtc_state))
> intel_dp_stop_link_train(intel_dp);
>
> @@ -3518,7 +3570,7 @@ static void tgl_ddi_pre_enable_dp(struct
> intel_encoder *encoder,
> * so not enabling it for now.
> */
>
> - /* 7.l */
> + /* 7l. Configure and enable FEC if needed */
> intel_ddi_enable_fec(encoder, crtc_state);
> intel_dsc_enable(encoder, crtc_state);
> }
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