Re: [Intel-gfx] [PATCH 04/14] drm/i915/tc: Fix system resume MST mode restore for DP-alt sinks

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Mar 16, 2023 at 03:17:14PM +0200, Imre Deak wrote:
> At least restoring the MST topology during system resume needs to use
> AUX before the display HW readout->sanitization sequence is complete,
> but on TC ports the PHY may be in the wrong mode for this, resulting in
> the AUX transfers to fail.
> 
> The initial TC port mode is kept fixed as BIOS left it for the above HW
> readout sequence (to prevent changing the mode on an enabled port).  If
> the port is disabled this initial mode is TBT - as in any case the PHY
> ownership is not held - even if a DP-alt sink is connected. Thus, the
> AUX transfers during this time will use TBT mode instead of the expected
> DP-alt mode and so time out.
> 
> Fix the above by connecting the PHY during port initialization if the
> port is disabled, which will switch to the expected mode (DP-alt in the
> above case).
> 
> As the encoder/pipe HW state isn't read-out yet at this point, check if
> the port is enabled based on the DDI_BUF enabled flag. Save the read-out
> initial mode, so intel_tc_port_sanitize_mode() can check this wrt. the
> read-out encoder HW state.
> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  .../drm/i915/display/intel_display_types.h    |  1 +
>  drivers/gpu/drm/i915/display/intel_tc.c       | 48 +++++++++++++++++--
>  2 files changed, 46 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index c32bfba06ca1f..06bbfd426ac70 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1783,6 +1783,7 @@ struct intel_digital_port {
>  	bool tc_legacy_port:1;
>  	char tc_port_name[8];
>  	enum tc_port_mode tc_mode;
> +	enum tc_port_mode tc_init_mode;
>  	enum phy_fia tc_phy_fia;
>  	u8 tc_phy_fia_idx;
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_tc.c b/drivers/gpu/drm/i915/display/intel_tc.c
> index fd826b9657e93..e8cf3b506fb7f 100644
> --- a/drivers/gpu/drm/i915/display/intel_tc.c
> +++ b/drivers/gpu/drm/i915/display/intel_tc.c
> @@ -118,6 +118,24 @@ assert_tc_cold_blocked(struct intel_digital_port *dig_port)
>  	drm_WARN_ON(&i915->drm, !enabled);
>  }
>  
> +static enum intel_display_power_domain
> +tc_port_power_domain(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);
> +
> +	return POWER_DOMAIN_PORT_DDI_LANES_TC1 + tc_port - TC_PORT_1;
> +}
> +
> +static void
> +assert_tc_port_power_enabled(struct intel_digital_port *dig_port)
> +{
> +	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
> +
> +	drm_WARN_ON(&i915->drm,
> +		    !intel_display_power_is_enabled(i915, tc_port_power_domain(dig_port)));
> +}
> +
>  u32 intel_tc_port_get_lane_mask(struct intel_digital_port *dig_port)
>  {
>  	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
> @@ -670,6 +688,16 @@ static void __intel_tc_port_put_link(struct intel_digital_port *dig_port)
>  	dig_port->tc_link_refcount--;
>  }
>  
> +static bool tc_port_is_enabled(struct intel_digital_port *dig_port)
> +{
> +	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
> +
> +	assert_tc_port_power_enabled(dig_port);
> +
> +	return intel_de_read(i915, DDI_BUF_CTL(dig_port->base.port)) &
> +	       DDI_BUF_CTL_ENABLE;
> +}
> +
>  /**
>   * intel_tc_port_init_mode: Read out HW state and init the given port's TypeC mode
>   * @dig_port: digital port
> @@ -692,9 +720,23 @@ void intel_tc_port_init_mode(struct intel_digital_port *dig_port)
>  	tc_cold_wref = tc_cold_block(dig_port, &domain);
>  
>  	dig_port->tc_mode = intel_tc_port_get_current_mode(dig_port);
> +	/*
> +	 * Save the initial mode for the state check in
> +	 * intel_tc_port_sanitize_mode().
> +	 */
> +	dig_port->tc_init_mode = dig_port->tc_mode;
> +	dig_port->tc_lock_wakeref = tc_cold_block(dig_port, &dig_port->tc_lock_power_domain);
> +
> +	/*
> +	 * The PHY needs to be connected for AUX to work during HW readout and
> +	 * MST topology resume, but the PHY mode can only be changed if the
> +	 * port is disabled.
> +	 */
> +	if (!tc_port_is_enabled(dig_port))
> +		intel_tc_port_update_mode(dig_port, 1, false);
> +
>  	/* Prevent changing dig_port->tc_mode until intel_tc_port_sanitize_mode() is called. */
>  	__intel_tc_port_get_link(dig_port);
> -	dig_port->tc_lock_wakeref = tc_cold_block(dig_port, &dig_port->tc_lock_power_domain);
>  
>  	tc_cold_unblock(dig_port, domain, tc_cold_wref);
>  
> @@ -741,11 +783,11 @@ void intel_tc_port_sanitize_mode(struct intel_digital_port *dig_port)
>  		 * we'll just switch to disconnected mode from it here without
>  		 * a note.
>  		 */
> -		if (dig_port->tc_mode != TC_PORT_TBT_ALT)
> +		if (dig_port->tc_init_mode != TC_PORT_TBT_ALT)
>  			drm_dbg_kms(&i915->drm,
>  				    "Port %s: PHY left in %s mode on disabled port, disconnecting it\n",
>  				    dig_port->tc_port_name,
> -				    tc_port_mode_name(dig_port->tc_mode));
> +				    tc_port_mode_name(dig_port->tc_init_mode));

So we just have the tc_init_mode to get the debug correct,
or was it supposed be used elsewhere too?

>  		icl_tc_phy_disconnect(dig_port);
>  		__intel_tc_port_put_link(dig_port);
>  
> -- 
> 2.37.1

-- 
Ville Syrjälä
Intel