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

Jani Nikula
2021-10-26T11:01:24Z

On Mon, 25 Oct 2021, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@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 Fix it up by not using the outdated port_mapping[] in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@vger.kernel.org
> Tested-by: Randy Dunlap <rdunlap@infradead.org>
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4138
> Signed-off-by: Ville Syrjälä <ville.syrjala@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