[Intel-gfx] [PATCH] drm/i915: Fix type1 DVI DP dual mode adapter heuristic for modern platforms

[Jani Nikula]

On Mon, 25 Oct 2021, Ville Syrjala <ville.syrjala at linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Looks like we never updated intel_bios_is_port_dp_dual_mode() when
> the VBT port mapping became erratic on modern platforms. This
> is causing us to look up the wrong child device and thus throwing
> the heuristic off (ie. we might end looking at a child device for
> a genuine DP++ port when we were supposed to look at one for a
> native HDMI port).
>
> Fix it up by not using the outdated port_mapping[] in
> intel_bios_is_port_dp_dual_mode() and rely on
> intel_bios_encoder_data_lookup() instead.

It's just crazy, we have like 7 port_mapping tables in intel_bios.c,
what happened?!

I wish we could unify all of this more.

>
> Cc: stable at vger.kernel.org
> Tested-by: Randy Dunlap <rdunlap at infradead.org>
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4138
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_bios.c | 85 +++++++++++++++++------
>  1 file changed, 63 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index f9776ca85de3..2b1423a43437 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -1707,6 +1707,39 @@ static void sanitize_aux_ch(struct intel_bios_encoder_data *devdata,
>  	child->aux_channel = 0;
>  }
>  
> +static u8 dvo_port_type(u8 dvo_port)
> +{
> +	switch (dvo_port) {
> +	case DVO_PORT_HDMIA:
> +	case DVO_PORT_HDMIB:
> +	case DVO_PORT_HDMIC:
> +	case DVO_PORT_HDMID:
> +	case DVO_PORT_HDMIE:
> +	case DVO_PORT_HDMIF:
> +	case DVO_PORT_HDMIG:
> +	case DVO_PORT_HDMIH:
> +	case DVO_PORT_HDMII:
> +		return DVO_PORT_HDMIA;
> +	case DVO_PORT_DPA:
> +	case DVO_PORT_DPB:
> +	case DVO_PORT_DPC:
> +	case DVO_PORT_DPD:
> +	case DVO_PORT_DPE:
> +	case DVO_PORT_DPF:
> +	case DVO_PORT_DPG:
> +	case DVO_PORT_DPH:
> +	case DVO_PORT_DPI:
> +		return DVO_PORT_DPA;
> +	case DVO_PORT_MIPIA:
> +	case DVO_PORT_MIPIB:
> +	case DVO_PORT_MIPIC:
> +	case DVO_PORT_MIPID:
> +		return DVO_PORT_MIPIA;
> +	default:
> +		return dvo_port;
> +	}
> +}
> +
>  static enum port __dvo_port_to_port(int n_ports, int n_dvo,
>  				    const int port_mapping[][3], u8 dvo_port)
>  {
> @@ -2623,35 +2656,17 @@ bool intel_bios_is_port_edp(struct drm_i915_private *i915, enum port port)
>  	return false;
>  }
>  
> -static bool child_dev_is_dp_dual_mode(const struct child_device_config *child,
> -				      enum port port)
> +static bool child_dev_is_dp_dual_mode(const struct child_device_config *child)
>  {
> -	static const struct {
> -		u16 dp, hdmi;
> -	} port_mapping[] = {
> -		/*
> -		 * Buggy VBTs may declare DP ports as having
> -		 * HDMI type dvo_port :( So let's check both.
> -		 */
> -		[PORT_B] = { DVO_PORT_DPB, DVO_PORT_HDMIB, },
> -		[PORT_C] = { DVO_PORT_DPC, DVO_PORT_HDMIC, },
> -		[PORT_D] = { DVO_PORT_DPD, DVO_PORT_HDMID, },
> -		[PORT_E] = { DVO_PORT_DPE, DVO_PORT_HDMIE, },
> -		[PORT_F] = { DVO_PORT_DPF, DVO_PORT_HDMIF, },
> -	};
> -
> -	if (port == PORT_A || port >= ARRAY_SIZE(port_mapping))
> -		return false;
> -
>  	if ((child->device_type & DEVICE_TYPE_DP_DUAL_MODE_BITS) !=
>  	    (DEVICE_TYPE_DP_DUAL_MODE & DEVICE_TYPE_DP_DUAL_MODE_BITS))
>  		return false;
>  
> -	if (child->dvo_port == port_mapping[port].dp)
> +	if (dvo_port_type(child->dvo_port) == DVO_PORT_DPA)
>  		return true;

I wonder, why do we care about dvo_port here, while we ignore the dvo
port DP/HDMI/DSI difference in parse_ddi_port()? I'm not really entirely
happy about adding another dvo port check method. :/

>  
>  	/* Only accept a HDMI dvo_port as DP++ if it has an AUX channel */
> -	if (child->dvo_port == port_mapping[port].hdmi &&
> +	if (dvo_port_type(child->dvo_port) == DVO_PORT_HDMIA &&
>  	    child->aux_channel != 0)
>  		return true;
>  
> @@ -2661,10 +2676,36 @@ static bool child_dev_is_dp_dual_mode(const struct child_device_config *child,
>  bool intel_bios_is_port_dp_dual_mode(struct drm_i915_private *i915,
>  				     enum port port)
>  {
> +	static const struct {
> +		u16 dp, hdmi;
> +	} port_mapping[] = {
> +		/*
> +		 * Buggy VBTs may declare DP ports as having
> +		 * HDMI type dvo_port :( So let's check both.
> +		 */
> +		[PORT_B] = { DVO_PORT_DPB, DVO_PORT_HDMIB, },
> +		[PORT_C] = { DVO_PORT_DPC, DVO_PORT_HDMIC, },
> +		[PORT_D] = { DVO_PORT_DPD, DVO_PORT_HDMID, },
> +		[PORT_E] = { DVO_PORT_DPE, DVO_PORT_HDMIE, },
> +		[PORT_F] = { DVO_PORT_DPF, DVO_PORT_HDMIF, },
> +	};
>  	const struct intel_bios_encoder_data *devdata;
>  
> +	if (HAS_DDI(i915)) {
> +		const struct intel_bios_encoder_data *devdata;
> +
> +		devdata = intel_bios_encoder_data_lookup(i915, port);
> +
> +		return devdata && child_dev_is_dp_dual_mode(&devdata->child);
> +	}
> +
> +	if (port == PORT_A || port >= ARRAY_SIZE(port_mapping))
> +		return false;
> +
>  	list_for_each_entry(devdata, &i915->vbt.display_devices, node) {
> -		if (child_dev_is_dp_dual_mode(&devdata->child, port))
> +		if ((devdata->child.dvo_port == port_mapping[port].dp ||
> +		     devdata->child.dvo_port == port_mapping[port].hdmi) &&
> +		    child_dev_is_dp_dual_mode(&devdata->child))
>  			return true;
>  	}

-- 
Jani Nikula, Intel Open Source Graphics Center