[Intel-xe] [PATCH 27/42] drm/i915/xe2lpd: Read pin assignment from IOM

[Matt Roper]

On Wed, Aug 23, 2023 at 10:07:25AM -0700, Lucas De Marchi wrote:
> From: Luca Coelho <luciano.coelho at intel.com>
> 
> Starting from display version 20, we need to read the pin assignment
> from the IOM TCSS_DDI_STATUS register instead of reading it from the
> FIA.
> 
> We use the pin assignment to decide the maximum lane count.  So, to
> support this change, add a new lnl_tc_port_get_max_lane_count() function
> that reads from the TCSS_DDI_STATUS register and decides the maximum
> lane count based on that.
> 
> BSpec: 69594
> Cc: Mika Kahola <mika.kahola at intel.com>
> Signed-off-by: Luca Coelho <luciano.coelho at intel.com>
> Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_tc.c | 28 +++++++++++++++++++++++++
>  drivers/gpu/drm/i915/i915_reg.h         |  1 +
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_tc.c b/drivers/gpu/drm/i915/display/intel_tc.c
> index 3c94bbcb5497..37b0f8529b4f 100644
> --- a/drivers/gpu/drm/i915/display/intel_tc.c
> +++ b/drivers/gpu/drm/i915/display/intel_tc.c
> @@ -290,6 +290,31 @@ u32 intel_tc_port_get_pin_assignment_mask(struct intel_digital_port *dig_port)
>  	       DP_PIN_ASSIGNMENT_SHIFT(tc->phy_fia_idx);
>  }
>  
> +static int lnl_tc_port_get_max_lane_count(struct intel_digital_port *dig_port)
> +{
> +	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
> +	enum tc_port tc_port = intel_port_to_tc(i915, dig_port->base.port);
> +	intel_wakeref_t wakeref;
> +	u32 val, pin_assignment;
> +
> +	with_intel_display_power(i915, POWER_DOMAIN_DISPLAY_CORE, wakeref)

Do we need this?  I don't think POWER_DOMAIN_DISPLAY_CORE has been tied
to any power wells since VLV/CHV.

Hmm, it looks like we actually grab it (and even assert it) in a bunch of
places on modern platforms that don't make sense to me since it isn't
tied to anything.

I guess leaving this here doesn't hurt anything, although we might want
to go back and take another look at this in the future.

Reviewed-by: Matt Roper <matthew.d.roper at intel.com>

> +		val = intel_de_read(i915, TCSS_DDI_STATUS(tc_port));
> +
> +	pin_assignment =
> +		REG_FIELD_GET(TCSS_DDI_STATUS_PIN_ASSIGNMENT_MASK, val);
> +
> +	switch (pin_assignment) {
> +	default:
> +		MISSING_CASE(pin_assignment);
> +		fallthrough;
> +	case DP_PIN_ASSIGNMENT_D:
> +		return 2;
> +	case DP_PIN_ASSIGNMENT_C:
> +	case DP_PIN_ASSIGNMENT_E:
> +		return 4;
> +	}
> +}
> +
>  static int mtl_tc_port_get_max_lane_count(struct intel_digital_port *dig_port)
>  {
>  	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
> @@ -348,6 +373,9 @@ int intel_tc_port_max_lane_count(struct intel_digital_port *dig_port)
>  
>  	assert_tc_cold_blocked(tc);
>  
> +	if (DISPLAY_VER(i915) >= 20)
> +		return lnl_tc_port_get_max_lane_count(dig_port);
> +
>  	if (DISPLAY_VER(i915) >= 14)
>  		return mtl_tc_port_get_max_lane_count(dig_port);
>  
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index e31a985b02d5..fa85530afac3 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6628,6 +6628,7 @@ enum skl_power_gate {
>  #define TCSS_DDI_STATUS(tc)			_MMIO(_PICK_EVEN(tc, \
>  								 _TCSS_DDI_STATUS_1, \
>  								 _TCSS_DDI_STATUS_2))
> +#define  TCSS_DDI_STATUS_PIN_ASSIGNMENT_MASK	REG_GENMASK(28, 25)
>  #define  TCSS_DDI_STATUS_READY			REG_BIT(2)
>  #define  TCSS_DDI_STATUS_HPD_LIVE_STATUS_TBT	REG_BIT(1)
>  #define  TCSS_DDI_STATUS_HPD_LIVE_STATUS_ALT	REG_BIT(0)
> -- 
> 2.40.1
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation