Re: [PATCH 2/2] drm/i915/bxt: WA for swapped HPD pins in A stepping

From: Imre Deak <imre.deak@intel.com>
To: Sonika Jindal <sonika.jindal@intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 2/2] drm/i915/bxt: WA for swapped HPD pins in A stepping
Date: Tue, 14 Jul 2015 17:22:24 +0300	[thread overview]
Message-ID: <1436883744.10749.43.camel@intel.com> (raw)
In-Reply-To: <1436852930-20830-2-git-send-email-sonika.jindal@intel.com>

On ti, 2015-07-14 at 11:18 +0530, Sonika Jindal wrote:
> As per bspec, on BXT A0/A1, sw needs to activate DDIA HPD logic
> and interrupts to check the external panel connection and DDIC HPD
> logic for edp panel.
> 
> Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c   |   18 ++++++++++++++++--
>  drivers/gpu/drm/i915/intel_hdmi.c |    9 ++++++++-
>  2 files changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 7b54b9d..c32f3d3 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -5869,10 +5869,24 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
>  	/* Set up the hotplug pin. */
>  	switch (port) {
>  	case PORT_A:
> -		intel_encoder->hpd_pin = HPD_PORT_A;
> +		/*
> +		 * On BXT A0/A1, sw needs to activate DDIC HPD logic and
> +		 * interrupts to check the eDP panel connection.
> +		 */
> +		if (IS_BROXTON(dev_priv) && (INTEL_REVID(dev) < BXT_REVID_B0))
> +			intel_encoder->hpd_pin = HPD_PORT_C;
> +		else
> +			intel_encoder->hpd_pin = HPD_PORT_A;
>  		break;
>  	case PORT_B:
> -		intel_encoder->hpd_pin = HPD_PORT_B;
> +		/*
> +		 * On BXT A0/A1, sw needs to activate DDIA HPD logic and
> +		 * interrupts to check the external panel connection.
> +		 */
> +		if (IS_BROXTON(dev_priv) && (INTEL_REVID(dev) < BXT_REVID_B0))
> +			intel_encoder->hpd_pin = HPD_PORT_A;
> +		else
> +			intel_encoder->hpd_pin = HPD_PORT_B;
>  		break;
>  	case PORT_C:
>  		intel_encoder->hpd_pin = HPD_PORT_C;

This won't work for a couple of reasons: atm i915_digport_work_func()
assumes a fixed pin->port mapping, for example it'll call the HPD
handler for the port A encoder for a short/long pulse event triggered
via the HPD_PORT_A pin, whereas after the above patch you want to select
port B's encoder on BXT A0/1. This could be fixed by setting up
hotplug.irq_port in intel_ddi_init() according to the above change, or
not using irq_port at all, but instead looking up the encoder the same
way i915_hotplug_work_func() does using intel_encoder->hpd_pin.

The HPD_PORT_A HPD handling is missing in general, see
for_each_hpd_pin() and intel_hpd_irq_handler()/is_dig_port. 

So if going with the above way, these issues need to be addressed first.

--Imre

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