--- /dev/null
+From 48eaeb7664c76139438724d520a1ea4a84a3ed92 Mon Sep 17 00:00:00 2001
+From: Jani Nikula <jani.nikula@intel.com>
+Date: Mon, 10 Jun 2019 12:30:54 +0300
+Subject: drm: add fallback override/firmware EDID modes workaround
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Jani Nikula <jani.nikula@intel.com>
+
+commit 48eaeb7664c76139438724d520a1ea4a84a3ed92 upstream.
+
+We've moved the override and firmware EDID (simply "override EDID" from
+now on) handling to the low level drm_do_get_edid() function in order to
+transparently use the override throughout the stack. The idea is that
+you get the override EDID via the ->get_modes() hook.
+
+Unfortunately, there are scenarios where the DDC probe in drm_get_edid()
+called via ->get_modes() fails, although the preceding ->detect()
+succeeds.
+
+In the case reported by Paul Wise, the ->detect() hook,
+intel_crt_detect(), relies on hotplug detect, bypassing the DDC. In the
+case reported by Ilpo Järvinen, there is no ->detect() hook, which is
+interpreted as connected. The subsequent DDC probe reached via
+->get_modes() fails, and we don't even look at the override EDID,
+resulting in no modes being added.
+
+Because drm_get_edid() is used via ->detect() all over the place, we
+can't trivially remove the DDC probe, as it leads to override EDID
+effectively meaning connector forcing. The goal is that connector
+forcing and override EDID remain orthogonal.
+
+Generally, the underlying problem here is the conflation of ->detect()
+and ->get_modes() via drm_get_edid(). The former should just detect, and
+the latter should just get the modes, typically via reading the EDID. As
+long as drm_get_edid() is used in ->detect(), it needs to retain the DDC
+probe. Or such users need to have a separate DDC probe step first.
+
+The EDID caching between ->detect() and ->get_modes() done by some
+drivers is a further complication that prevents us from making
+drm_do_get_edid() adapt to the two cases.
+
+Work around the regression by falling back to a separate attempt at
+getting the override EDID at drm_helper_probe_single_connector_modes()
+level. With a working DDC and override EDID, it'll never be called; the
+override EDID will come via ->get_modes(). There will still be a failing
+DDC probe attempt in the cases that require the fallback.
+
+v2:
+- Call drm_connector_update_edid_property (Paul)
+- Update commit message about EDID caching (Daniel)
+
+Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107583
+Reported-by: Paul Wise <pabs3@bonedaddy.net>
+Cc: Paul Wise <pabs3@bonedaddy.net>
+References: http://mid.mail-archive.com/alpine.DEB.2.20.1905262211270.24390@whs-18.cs.helsinki.fi
+Reported-by: Ilpo Järvinen <ilpo.jarvinen@cs.helsinki.fi>
+Cc: Ilpo Järvinen <ilpo.jarvinen@cs.helsinki.fi>
+Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
+References: 15f080f08d48 ("drm/edid: respect connector force for drm_get_edid ddc probe")
+Fixes: 53fd40a90f3c ("drm: handle override and firmware EDID at drm_do_get_edid() level")
+Cc: <stable@vger.kernel.org> # v4.15+ 56a2b7f2a39a drm/edid: abstract override/firmware EDID retrieval
+Cc: <stable@vger.kernel.org> # v4.15+
+Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
+Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
+Cc: Harish Chegondi <harish.chegondi@intel.com>
+Tested-by: Paul Wise <pabs3@bonedaddy.net>
+Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
+Signed-off-by: Jani Nikula <jani.nikula@intel.com>
+Link: https://patchwork.freedesktop.org/patch/msgid/20190610093054.28445-1-jani.nikula@intel.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/gpu/drm/drm_edid.c | 30 ++++++++++++++++++++++++++++++
+ drivers/gpu/drm/drm_probe_helper.c | 7 +++++++
+ include/drm/drm_edid.h | 1 +
+ 3 files changed, 38 insertions(+)
+
+--- a/drivers/gpu/drm/drm_edid.c
++++ b/drivers/gpu/drm/drm_edid.c
+@@ -1595,6 +1595,36 @@ static struct edid *drm_get_override_edi
+ }
+
+ /**
++ * drm_add_override_edid_modes - add modes from override/firmware EDID
++ * @connector: connector we're probing
++ *
++ * Add modes from the override/firmware EDID, if available. Only to be used from
++ * drm_helper_probe_single_connector_modes() as a fallback for when DDC probe
++ * failed during drm_get_edid() and caused the override/firmware EDID to be
++ * skipped.
++ *
++ * Return: The number of modes added or 0 if we couldn't find any.
++ */
++int drm_add_override_edid_modes(struct drm_connector *connector)
++{
++ struct edid *override;
++ int num_modes = 0;
++
++ override = drm_get_override_edid(connector);
++ if (override) {
++ drm_connector_update_edid_property(connector, override);
++ num_modes = drm_add_edid_modes(connector, override);
++ kfree(override);
++
++ DRM_DEBUG_KMS("[CONNECTOR:%d:%s] adding %d modes via fallback override/firmware EDID\n",
++ connector->base.id, connector->name, num_modes);
++ }
++
++ return num_modes;
++}
++EXPORT_SYMBOL(drm_add_override_edid_modes);
++
++/**
+ * drm_do_get_edid - get EDID data using a custom EDID block read function
+ * @connector: connector we're probing
+ * @get_edid_block: EDID block read function
+--- a/drivers/gpu/drm/drm_probe_helper.c
++++ b/drivers/gpu/drm/drm_probe_helper.c
+@@ -479,6 +479,13 @@ retry:
+
+ count = (*connector_funcs->get_modes)(connector);
+
++ /*
++ * Fallback for when DDC probe failed in drm_get_edid() and thus skipped
++ * override/firmware EDID.
++ */
++ if (count == 0 && connector->status == connector_status_connected)
++ count = drm_add_override_edid_modes(connector);
++
+ if (count == 0 && connector->status == connector_status_connected)
+ count = drm_add_modes_noedid(connector, 1024, 768);
+ count += drm_helper_probe_add_cmdline_mode(connector);
+--- a/include/drm/drm_edid.h
++++ b/include/drm/drm_edid.h
+@@ -465,6 +465,7 @@ struct edid *drm_get_edid_switcheroo(str
+ struct i2c_adapter *adapter);
+ struct edid *drm_edid_duplicate(const struct edid *edid);
+ int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid);
++int drm_add_override_edid_modes(struct drm_connector *connector);
+
+ u8 drm_match_cea_mode(const struct drm_display_mode *to_match);
+ enum hdmi_picture_aspect drm_get_cea_aspect_ratio(const u8 video_code);
--- /dev/null
+From 56a2b7f2a39a8d4b16a628e113decde3d7400879 Mon Sep 17 00:00:00 2001
+From: Jani Nikula <jani.nikula@intel.com>
+Date: Fri, 7 Jun 2019 14:05:12 +0300
+Subject: drm/edid: abstract override/firmware EDID retrieval
+
+From: Jani Nikula <jani.nikula@intel.com>
+
+commit 56a2b7f2a39a8d4b16a628e113decde3d7400879 upstream.
+
+Abstract the debugfs override and the firmware EDID retrieval
+function. We'll be needing it in the follow-up. No functional changes.
+
+Cc: Daniel Vetter <daniel@ffwll.ch>
+Cc: Harish Chegondi <harish.chegondi@intel.com>
+Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
+Tested-by: Tested-by: Paul Wise <pabs3@bonedaddy.net>
+Signed-off-by: Jani Nikula <jani.nikula@intel.com>
+Link: https://patchwork.freedesktop.org/patch/msgid/20190607110513.12072-1-jani.nikula@intel.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/gpu/drm/drm_edid.c | 25 +++++++++++++++++--------
+ 1 file changed, 17 insertions(+), 8 deletions(-)
+
+--- a/drivers/gpu/drm/drm_edid.c
++++ b/drivers/gpu/drm/drm_edid.c
+@@ -1580,6 +1580,20 @@ static void connector_bad_edid(struct dr
+ }
+ }
+
++/* Get override or firmware EDID */
++static struct edid *drm_get_override_edid(struct drm_connector *connector)
++{
++ struct edid *override = NULL;
++
++ if (connector->override_edid)
++ override = drm_edid_duplicate(connector->edid_blob_ptr->data);
++
++ if (!override)
++ override = drm_load_edid_firmware(connector);
++
++ return IS_ERR(override) ? NULL : override;
++}
++
+ /**
+ * drm_do_get_edid - get EDID data using a custom EDID block read function
+ * @connector: connector we're probing
+@@ -1607,15 +1621,10 @@ struct edid *drm_do_get_edid(struct drm_
+ {
+ int i, j = 0, valid_extensions = 0;
+ u8 *edid, *new;
+- struct edid *override = NULL;
+-
+- if (connector->override_edid)
+- override = drm_edid_duplicate(connector->edid_blob_ptr->data);
+-
+- if (!override)
+- override = drm_load_edid_firmware(connector);
++ struct edid *override;
+
+- if (!IS_ERR_OR_NULL(override))
++ override = drm_get_override_edid(connector);
++ if (override)
+ return override;
+
+ if ((edid = kmalloc(EDID_LENGTH, GFP_KERNEL)) == NULL)
projects / thirdparty / kernel / stable-queue.git / commitdiff
