queue-5.1/drm-add-fallback-override-firmware-edid-modes-workaround.patch

   1 From 48eaeb7664c76139438724d520a1ea4a84a3ed92 Mon Sep 17 00:00:00 2001
   2 From: Jani Nikula <jani.nikula@intel.com>
   3 Date: Mon, 10 Jun 2019 12:30:54 +0300
   4 Subject: drm: add fallback override/firmware EDID modes workaround
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 From: Jani Nikula <jani.nikula@intel.com>
  10
  11 commit 48eaeb7664c76139438724d520a1ea4a84a3ed92 upstream.
  12
  13 We've moved the override and firmware EDID (simply "override EDID" from
  14 now on) handling to the low level drm_do_get_edid() function in order to
  15 transparently use the override throughout the stack. The idea is that
  16 you get the override EDID via the ->get_modes() hook.
  17
  18 Unfortunately, there are scenarios where the DDC probe in drm_get_edid()
  19 called via ->get_modes() fails, although the preceding ->detect()
  20 succeeds.
  21
  22 In the case reported by Paul Wise, the ->detect() hook,
  23 intel_crt_detect(), relies on hotplug detect, bypassing the DDC. In the
  24 case reported by Ilpo Järvinen, there is no ->detect() hook, which is
  25 interpreted as connected. The subsequent DDC probe reached via
  26 ->get_modes() fails, and we don't even look at the override EDID,
  27 resulting in no modes being added.
  28
  29 Because drm_get_edid() is used via ->detect() all over the place, we
  30 can't trivially remove the DDC probe, as it leads to override EDID
  31 effectively meaning connector forcing. The goal is that connector
  32 forcing and override EDID remain orthogonal.
  33
  34 Generally, the underlying problem here is the conflation of ->detect()
  35 and ->get_modes() via drm_get_edid(). The former should just detect, and
  36 the latter should just get the modes, typically via reading the EDID. As
  37 long as drm_get_edid() is used in ->detect(), it needs to retain the DDC
  38 probe. Or such users need to have a separate DDC probe step first.
  39
  40 The EDID caching between ->detect() and ->get_modes() done by some
  41 drivers is a further complication that prevents us from making
  42 drm_do_get_edid() adapt to the two cases.
  43
  44 Work around the regression by falling back to a separate attempt at
  45 getting the override EDID at drm_helper_probe_single_connector_modes()
  46 level. With a working DDC and override EDID, it'll never be called; the
  47 override EDID will come via ->get_modes(). There will still be a failing
  48 DDC probe attempt in the cases that require the fallback.
  49
  50 v2:
  51 - Call drm_connector_update_edid_property (Paul)
  52 - Update commit message about EDID caching (Daniel)
  53
  54 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107583
  55 Reported-by: Paul Wise <pabs3@bonedaddy.net>
  56 Cc: Paul Wise <pabs3@bonedaddy.net>
  57 References: http://mid.mail-archive.com/alpine.DEB.2.20.1905262211270.24390@whs-18.cs.helsinki.fi
  58 Reported-by: Ilpo Järvinen <ilpo.jarvinen@cs.helsinki.fi>
  59 Cc: Ilpo Järvinen <ilpo.jarvinen@cs.helsinki.fi>
  60 Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
  61 References: 15f080f08d48 ("drm/edid: respect connector force for drm_get_edid ddc probe")
  62 Fixes: 53fd40a90f3c ("drm: handle override and firmware EDID at drm_do_get_edid() level")
  63 Cc: <stable@vger.kernel.org> # v4.15+ 56a2b7f2a39a drm/edid: abstract override/firmware EDID retrieval
  64 Cc: <stable@vger.kernel.org> # v4.15+
  65 Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
  66 Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
  67 Cc: Harish Chegondi <harish.chegondi@intel.com>
  68 Tested-by: Paul Wise <pabs3@bonedaddy.net>
  69 Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
  70 Signed-off-by: Jani Nikula <jani.nikula@intel.com>
  71 Link: https://patchwork.freedesktop.org/patch/msgid/20190610093054.28445-1-jani.nikula@intel.com
  72 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  73
  74 ---
  75  drivers/gpu/drm/drm_edid.c         |   30 ++++++++++++++++++++++++++++++
  76  drivers/gpu/drm/drm_probe_helper.c |    7 +++++++
  77  include/drm/drm_edid.h             |    1 +
  78  3 files changed, 38 insertions(+)
  79
  80 --- a/drivers/gpu/drm/drm_edid.c
  81 +++ b/drivers/gpu/drm/drm_edid.c
  82 @@ -1595,6 +1595,36 @@ static struct edid *drm_get_override_edi
  83  }
  84
  85  /**
  86 + * drm_add_override_edid_modes - add modes from override/firmware EDID
  87 + * @connector: connector we're probing
  88 + *
  89 + * Add modes from the override/firmware EDID, if available. Only to be used from
  90 + * drm_helper_probe_single_connector_modes() as a fallback for when DDC probe
  91 + * failed during drm_get_edid() and caused the override/firmware EDID to be
  92 + * skipped.
  93 + *
  94 + * Return: The number of modes added or 0 if we couldn't find any.
  95 + */
  96 +int drm_add_override_edid_modes(struct drm_connector *connector)
  97 +{
  98 +       struct edid *override;
  99 +       int num_modes = 0;
 100 +
 101 +       override = drm_get_override_edid(connector);
 102 +       if (override) {
 103 +               drm_connector_update_edid_property(connector, override);
 104 +               num_modes = drm_add_edid_modes(connector, override);
 105 +               kfree(override);
 106 +
 107 +               DRM_DEBUG_KMS("[CONNECTOR:%d:%s] adding %d modes via fallback override/firmware EDID\n",
 108 +                             connector->base.id, connector->name, num_modes);
 109 +       }
 110 +
 111 +       return num_modes;
 112 +}
 113 +EXPORT_SYMBOL(drm_add_override_edid_modes);
 114 +
 115 +/**
 116   * drm_do_get_edid - get EDID data using a custom EDID block read function
 117   * @connector: connector we're probing
 118   * @get_edid_block: EDID block read function
 119 --- a/drivers/gpu/drm/drm_probe_helper.c
 120 +++ b/drivers/gpu/drm/drm_probe_helper.c
 121 @@ -479,6 +479,13 @@ retry:
 122
 123         count = (*connector_funcs->get_modes)(connector);
 124
 125 +       /*
 126 +        * Fallback for when DDC probe failed in drm_get_edid() and thus skipped
 127 +        * override/firmware EDID.
 128 +        */
 129 +       if (count == 0 && connector->status == connector_status_connected)
 130 +               count = drm_add_override_edid_modes(connector);
 131 +
 132         if (count == 0 && connector->status == connector_status_connected)
 133                 count = drm_add_modes_noedid(connector, 1024, 768);
 134         count += drm_helper_probe_add_cmdline_mode(connector);
 135 --- a/include/drm/drm_edid.h
 136 +++ b/include/drm/drm_edid.h
 137 @@ -465,6 +465,7 @@ struct edid *drm_get_edid_switcheroo(str
 138                                      struct i2c_adapter *adapter);
 139  struct edid *drm_edid_duplicate(const struct edid *edid);
 140  int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid);
 141 +int drm_add_override_edid_modes(struct drm_connector *connector);
 142
 143  u8 drm_match_cea_mode(const struct drm_display_mode *to_match);
 144  enum hdmi_picture_aspect drm_get_cea_aspect_ratio(const u8 video_code);