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drm/i915: Favor last VBT child device with conflicting AUX ch/DDC pin

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The first come first served apporoach to handling the VBT
child device AUX ch conflicts has backfired. We have machines
in the wild where the VBT specifies both port A eDP and
port E DP (in that order) with port E being the real one.

So let's try to flip the preference around and let the last
child device win once again.

Cc: stable@vger.kernel.org
Cc: Jani Nikula <jani.nikula@intel.com>
Tested-by: Masami Ichikawa <masami256@gmail.com>
Tested-by: Torsten <freedesktop201910@liggy.de>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111966
Fixes: 36a0f92020 ("drm/i915/bios: make child device order the priority order")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191011202030.8829-1-ville.syrjala@linux.intel.com
Acked-by: Jani Nikula <jani.nikula@intel.com>
This commit is contained in:
Ville Syrjälä 2019-10-11 23:20:30 +03:00
parent 89b6d1831d
commit 41e35ffb38
1 changed files with 16 additions and 6 deletions
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22
drivers/gpu/drm/i915/display/intel_bios.c
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@ -1270,7 +1270,7 @@ static void sanitize_ddc_pin(struct drm_i915_private *dev_priv,
DRM_DEBUG_KMS("port %c trying to use the same DDC pin (0x%x) as port %c, "
"disabling port %c DVI/HDMI support\n",
port_name(port), info->alternate_ddc_pin,
port_name(p), port_name(port));
port_name(p), port_name(p));
/*
* If we have multiple ports supposedly sharing the
@ -1278,9 +1278,14 @@ static void sanitize_ddc_pin(struct drm_i915_private *dev_priv,
* port. Otherwise they share the same ddc bin and
* system couldn't communicate with them separately.
*
* Give child device order the priority, first come first
* served.
* Give inverse child device order the priority,
* last one wins. Yes, there are real machines
* (eg. Asrock B250M-HDV) where VBT has both
* port A and port E with the same AUX ch and
* we must pick port E :(
*/
info = &dev_priv->vbt.ddi_port_info[p];
info->supports_dvi = false;
info->supports_hdmi = false;
info->alternate_ddc_pin = 0;
@ -1316,7 +1321,7 @@ static void sanitize_aux_ch(struct drm_i915_private *dev_priv,
DRM_DEBUG_KMS("port %c trying to use the same AUX CH (0x%x) as port %c, "
"disabling port %c DP support\n",
port_name(port), info->alternate_aux_channel,
port_name(p), port_name(port));
port_name(p), port_name(p));
/*
* If we have multiple ports supposedlt sharing the
@ -1324,9 +1329,14 @@ static void sanitize_aux_ch(struct drm_i915_private *dev_priv,
* port. Otherwise they share the same aux channel
* and system couldn't communicate with them separately.
*
* Give child device order the priority, first come first
* served.
* Give inverse child device order the priority,
* last one wins. Yes, there are real machines
* (eg. Asrock B250M-HDV) where VBT has both
* port A and port E with the same AUX ch and
* we must pick port E :(
*/
info = &dev_priv->vbt.ddi_port_info[p];
info->supports_dp = false;
info->alternate_aux_channel = 0;
}