Re: [PATCH 04/25] drm/i915/ltphy: Program sequence for PORT_CLOCK_CTL for LT Phy

["Murthy, Arun R" <arun.r.murthy@intel.com>]

On 15-10-2025 09:37, Suraj Kandpal wrote:
> Program sequence from port clock ctl except for the SSC
> enablement part which will be taken care of later.
>
> Bspec: 74492
> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> ---
>   drivers/gpu/drm/i915/display/intel_cx0_phy.c |  8 ++---
>   drivers/gpu/drm/i915/display/intel_cx0_phy.h |  1 +
>   drivers/gpu/drm/i915/display/intel_lt_phy.c  | 36 ++++++++++++++++++++
>   3 files changed, 41 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.c b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> index db2b05521c62..eab49c08d7ff 100644
> --- a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> +++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> @@ -2585,7 +2585,7 @@ static bool is_dp2(u32 clock)
>   	return false;
>   }
>   
> -static bool is_hdmi_frl(u32 clock)
> +bool intel_cx0_is_hdmi_frl(u32 clock)
>   {
>   	switch (clock) {
>   	case 300000: /* 3 Gbps */
> @@ -2612,7 +2612,7 @@ static int intel_get_c20_custom_width(u32 clock, bool dp)
>   {
>   	if (dp && is_dp2(clock))
>   		return 2;
> -	else if (is_hdmi_frl(clock))
> +	else if (intel_cx0_is_hdmi_frl(clock))
>   		return 1;
>   	else
>   		return 0;
> @@ -2706,7 +2706,7 @@ static void intel_c20_pll_program(struct intel_display *display,
>   	} else {
>   		intel_cx0_rmw(encoder, owned_lane_mask, PHY_C20_VDR_CUSTOM_SERDES_RATE,
>   			      BIT(7) | PHY_C20_CUSTOM_SERDES_MASK,
> -			      is_hdmi_frl(port_clock) ? BIT(7) : 0,
> +			      intel_cx0_is_hdmi_frl(port_clock) ? BIT(7) : 0,
>   			      MB_WRITE_COMMITTED);
>   
>   		intel_cx0_write(encoder, INTEL_CX0_BOTH_LANES, PHY_C20_VDR_HDMI_RATE,
> @@ -2766,7 +2766,7 @@ static void intel_program_port_clock_ctl(struct intel_encoder *encoder,
>   
>   	val |= XELPDP_FORWARD_CLOCK_UNGATE;
>   
> -	if (!is_dp && is_hdmi_frl(port_clock))
> +	if (!is_dp && intel_cx0_is_hdmi_frl(port_clock))
Would it be better to move this to a different patch?
>   		val |= XELPDP_DDI_CLOCK_SELECT_PREP(display, XELPDP_DDI_CLOCK_SELECT_DIV18CLK);
>   	else
>   		val |= XELPDP_DDI_CLOCK_SELECT_PREP(display, XELPDP_DDI_CLOCK_SELECT_MAXPCLK);
> diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.h b/drivers/gpu/drm/i915/display/intel_cx0_phy.h
> index c92026fe7b8f..b111a893b428 100644
> --- a/drivers/gpu/drm/i915/display/intel_cx0_phy.h
> +++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.h
> @@ -43,6 +43,7 @@ void intel_cx0_phy_set_signal_levels(struct intel_encoder *encoder,
>   				     const struct intel_crtc_state *crtc_state);
>   int intel_cx0_phy_check_hdmi_link_rate(struct intel_hdmi *hdmi, int clock);
>   void intel_cx0_setup_powerdown(struct intel_encoder *encoder);
> +bool intel_cx0_is_hdmi_frl(u32 clock);
>   int intel_mtl_tbt_calc_port_clock(struct intel_encoder *encoder);
>   void intel_cx0_pll_power_save_wa(struct intel_display *display);
>   void intel_lnl_mac_transmit_lfps(struct intel_encoder *encoder,
> diff --git a/drivers/gpu/drm/i915/display/intel_lt_phy.c b/drivers/gpu/drm/i915/display/intel_lt_phy.c
> index c65333cc9494..8c6f60d9e0ac 100644
> --- a/drivers/gpu/drm/i915/display/intel_lt_phy.c
> +++ b/drivers/gpu/drm/i915/display/intel_lt_phy.c
> @@ -108,13 +108,49 @@ intel_lt_phy_lane_reset(struct intel_encoder *encoder,
>   	intel_de_rmw(display, XELPDP_PORT_BUF_CTL2(display, port), lane_phy_pulse_status, 0);
>   }
>   
> +static void
> +intel_lt_phy_program_port_clock_ctl(struct intel_encoder *encoder,
> +				    const struct intel_crtc_state *crtc_state,
> +				    bool lane_reversal)
> +{
> +	struct intel_display *display = to_intel_display(encoder);
> +	u32 val = 0;
> +
> +	intel_de_rmw(display, XELPDP_PORT_BUF_CTL1(display, encoder->port),
> +		     XELPDP_PORT_REVERSAL,
> +		     lane_reversal ? XELPDP_PORT_REVERSAL : 0);
> +
> +	val |= XELPDP_FORWARD_CLOCK_UNGATE;
> +
> +	/*
> +	 * We actually mean MACCLK here and not MAXPCLK when using LT Phy
> +	 * but since the register bits still remain the same we use
> +	 * the same definition
> +	 */
> +	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI) &&
> +	    intel_cx0_is_hdmi_frl(crtc_state->port_clock))
> +		val |= XELPDP_DDI_CLOCK_SELECT_PREP(display, XELPDP_DDI_CLOCK_SELECT_DIV18CLK);
> +	else
> +		val |= XELPDP_DDI_CLOCK_SELECT_PREP(display, XELPDP_DDI_CLOCK_SELECT_MAXPCLK);
> +
> +	intel_de_rmw(display, XELPDP_PORT_CLOCK_CTL(display, encoder->port),
> +		     XELPDP_LANE1_PHY_CLOCK_SELECT | XELPDP_FORWARD_CLOCK_UNGATE |
> +		     XELPDP_DDI_CLOCK_SELECT_MASK(display) | XELPDP_SSC_ENABLE_PLLA |
> +		     XELPDP_SSC_ENABLE_PLLB, val);
> +}
> +
>   void intel_lt_phy_pll_enable(struct intel_encoder *encoder,
>   			     const struct intel_crtc_state *crtc_state)
>   {
> +	struct intel_digital_port *dig_port = enc_to_dig_port(encoder);
> +	bool lane_reversal = dig_port->lane_reversal;
> +
>   	/* 1. Enable MacCLK at default 162 MHz frequency. */
>   	intel_lt_phy_lane_reset(encoder, crtc_state->lane_count);
>   
>   	/* 2. Program PORT_CLOCK_CTL register to configure clock muxes, gating, and SSC. */
> +	intel_lt_phy_program_port_clock_ctl(encoder, crtc_state, lane_reversal);
> +
>   	/* 3. Change owned PHY lanes power to Ready state. */
>   	/*
>   	 * 4. Read the PHY message bus VDR register PHY_VDR_0_Config check enabled PLL type,