Re: [PATCH 01/19] drm/i915/lnl+/tc: Fix handling of an enabled/disconnected dp-alt sink

[Luca Coelho <luca@coelho.fi>]

On Tue, 2025-08-05 at 10:36 +0300, Imre Deak wrote:
> The TypeC PHY HW readout during driver loading and system resume
> determines which TypeC mode the PHY is in (legacy/DP-alt/TBT-alt) and
> whether the PHY is connected, based on the PHY's Owned and Ready flags.
> For the PHY to be in DP-alt or legacy mode and for the PHY to be in the
> connected state in these modes, both the Owned (set by the BIOS/driver)
> and the Ready (set by the HW) flags should be set.
> 
> On ICL-MTL the HW kept the PHY's Ready flag set after the driver
> connected the PHY by acquiring the PHY ownership (by setting the Owned
> flag), until the driver disconnected the PHY by releasing the PHY
> ownership (by clearing the Owned flag). On LNL+ this has changed, in
> that the HW clears the Ready flag as soon as the sink gets disconnected,
> even if the PHY ownership was acquired already and hence the PHY is
> being used by the display.
> 
> When inheriting the HW state from BIOS for a PHY connected in DP-alt
> mode on which the sink got disconnected - i.e. in a case where the sink
> was connected while BIOS/GOP was running and so the sink got enabled
> connecting the PHY, but the user disconnected the sink by the time the
> driver loaded - the PHY Owned but not Ready state must be accounted for
> on LNL+ according to the above. Do that by assuming on LNL+ that the PHY
> is connected in DP-alt mode whenever the PHY Owned flag is set,
> regardless of the PHY Ready flag.
> 
> This fixes a problem on LNL+, where the PHY TypeC mode / connected state
> was detected incorrectly for a DP-alt sink, which got connected and then
> disconnected by the user in the above way.
> 
> Cc: stable@vger.kernel.org # v6.8+
> Reported-by: Charlton Lin <charlton.lin@intel.com>
> Tested-by: Khaled Almahallawy <khaled.almahallawy@intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_tc.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_tc.c b/drivers/gpu/drm/i915/display/intel_tc.c
> index 3bc57579fe53e..73a08bd84a70a 100644
> --- a/drivers/gpu/drm/i915/display/intel_tc.c
> +++ b/drivers/gpu/drm/i915/display/intel_tc.c
> @@ -1226,14 +1226,18 @@ static void tc_phy_get_hw_state(struct intel_tc_port *tc)
>  	tc->phy_ops->get_hw_state(tc);
>  }
>  
> -static bool tc_phy_is_ready_and_owned(struct intel_tc_port *tc,
> -				      bool phy_is_ready, bool phy_is_owned)
> +static bool tc_phy_in_legacy_or_dp_alt_mode(struct intel_tc_port *tc,
> +					    bool phy_is_ready, bool phy_is_owned)

Personally I don't like the "or" in the function name.  You're
returning a boolean which is true or false.  The return value is akin
to answering "Yes/No" to the question "Is it black or white".

This is a nitpick, obviously, so I'll leave it up to you.

Regardless:

Reviewed-by: Luca Coelho <luciano.coelho@intel.com>

--
Cheers,
Luca.

>  {
>  	struct intel_display *display = to_intel_display(tc->dig_port);
>  
> -	drm_WARN_ON(display->drm, phy_is_owned && !phy_is_ready);
> +	if (DISPLAY_VER(display) < 20) {
> +		drm_WARN_ON(display->drm, phy_is_owned && !phy_is_ready);
>  
> -	return phy_is_ready && phy_is_owned;
> +		return phy_is_ready && phy_is_owned;
> +	} else {
> +		return phy_is_owned;
> +	}
>  }
>  
>  static bool tc_phy_is_connected(struct intel_tc_port *tc,
> @@ -1244,7 +1248,7 @@ static bool tc_phy_is_connected(struct intel_tc_port *tc,
>  	bool phy_is_owned = tc_phy_is_owned(tc);
>  	bool is_connected;
>  
> -	if (tc_phy_is_ready_and_owned(tc, phy_is_ready, phy_is_owned))
> +	if (tc_phy_in_legacy_or_dp_alt_mode(tc, phy_is_ready, phy_is_owned))
>  		is_connected = port_pll_type == ICL_PORT_DPLL_MG_PHY;
>  	else
>  		is_connected = port_pll_type == ICL_PORT_DPLL_DEFAULT;
> @@ -1352,7 +1356,7 @@ tc_phy_get_current_mode(struct intel_tc_port *tc)
>  	phy_is_ready = tc_phy_is_ready(tc);
>  	phy_is_owned = tc_phy_is_owned(tc);
>  
> -	if (!tc_phy_is_ready_and_owned(tc, phy_is_ready, phy_is_owned)) {
> +	if (!tc_phy_in_legacy_or_dp_alt_mode(tc, phy_is_ready, phy_is_owned)) {
>  		mode = get_tc_mode_in_phy_not_owned_state(tc, live_mode);
>  	} else {
>  		drm_WARN_ON(display->drm, live_mode == TC_PORT_TBT_ALT);