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monitor-manager-kms: Don't try to wait for EDID on hot plug

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The mitigation to avoid missing EDID blob was incorrect; the reason it
sometimes failed to read was a race between different applications all
trying to read the EDID at the same time. E.g. gnome-shell as GDM would
at the same time as the session gnome-shell try to read the EDID of the
same connector at the same time, triggering a race in the kernel,
making the blob reading ioctl occationally fail with ENOENT.

Remove this mitigation, as it didn't really mitigate anything; the race
could just as well happen when doing the actual read later.

https://bugzilla.gnome.org/show_bug.cgi?id=779837
This commit is contained in:
Jonas Ådahl 2017-03-10 16:55:53 +08:00
parent db14e6099e
commit eb3ff3f44a
1 changed files with 0 additions and 130 deletions
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130
src/backends/native/meta-monitor-manager-kms.c
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@ -52,10 +52,6 @@
#define ALL_TRANSFORMS_MASK ((1 << ALL_TRANSFORMS) - 1)
#define SYNC_TOLERANCE 0.01 /* 1 percent */
/* Try each 50 milleseconds up to half a second to get a proper EDID read */
#define EDID_RETRY_TIMEOUT_MS 50
#define EDID_MAX_NUM_RETRIES 10
typedef struct
{
drmModeConnector *connector;
@ -117,9 +113,6 @@ struct _MetaMonitorManagerKms
GSettings *desktop_settings;
gboolean page_flips_not_supported;
guint handle_hotplug_timeout;
int read_edid_tries;
};
struct _MetaMonitorManagerKmsClass
@ -1595,76 +1588,6 @@ meta_monitor_manager_kms_set_crtc_gamma (MetaMonitorManager *manager,
drmModeCrtcSetGamma (manager_kms->fd, crtc->crtc_id, size, red, green, blue);
}
static gboolean
has_pending_edid_blob (MetaMonitorManagerKms *manager_kms)
{
drmModeRes *resources;
int n_connectors;
int i, j;
gboolean edid_blob_pending;
resources = drmModeGetResources (manager_kms->fd);
n_connectors = resources->count_connectors;
edid_blob_pending = FALSE;
for (i = 0; i < n_connectors; i++)
{
drmModeConnector *drm_connector;
uint32_t edid_blob_id;
drm_connector = drmModeGetConnector (manager_kms->fd,
resources->connectors[i]);
edid_blob_id = 0;
for (j = 0; j < drm_connector->count_props; j++)
{
drmModePropertyPtr prop;
prop = drmModeGetProperty (manager_kms->fd, drm_connector->props[j]);
if (prop->flags & DRM_MODE_PROP_BLOB &&
g_str_equal (prop->name, "EDID"))
edid_blob_id = drm_connector->prop_values[j];
drmModeFreeProperty (prop);
if (edid_blob_id)
break;
}
drmModeFreeConnector (drm_connector);
if (edid_blob_id)
{
GError *error = NULL;
drmModePropertyBlobPtr edid_blob;
edid_blob = read_edid_blob (manager_kms, edid_blob_id, &error);
if (!edid_blob &&
g_error_matches (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND))
{
edid_blob_pending = TRUE;
g_error_free (error);
}
else if (!edid_blob)
{
g_error_free (error);
}
else
{
drmModeFreePropertyBlob (edid_blob);
}
}
if (edid_blob_pending)
break;
}
drmModeFreeResources (resources);
return edid_blob_pending;
}
static void
handle_hotplug_event (MetaMonitorManager *manager)
{
@ -1672,37 +1595,6 @@ handle_hotplug_event (MetaMonitorManager *manager)
meta_monitor_manager_on_hotplug (manager);
}
static gboolean
handle_hotplug_event_timeout (gpointer user_data)
{
MetaMonitorManager *manager = user_data;
MetaMonitorManagerKms *manager_kms = META_MONITOR_MANAGER_KMS (user_data);
if (!has_pending_edid_blob (manager_kms))
{
handle_hotplug_event (manager);
manager_kms->handle_hotplug_timeout = 0;
return G_SOURCE_REMOVE;
}
manager_kms->read_edid_tries++;
if (manager_kms->read_edid_tries > EDID_MAX_NUM_RETRIES)
{
g_warning ("Tried to read the EDID %d times, "
"but one or more are still missing, continuing without",
manager_kms->read_edid_tries);
handle_hotplug_event (manager);
manager_kms->handle_hotplug_timeout = 0;
return G_SOURCE_REMOVE;
}
return G_SOURCE_CONTINUE;
}
static void
on_uevent (GUdevClient *client,
const char *action,
@ -1715,28 +1607,6 @@ on_uevent (GUdevClient *client,
if (!g_udev_device_get_property_as_boolean (device, "HOTPLUG"))
return;
if (manager_kms->handle_hotplug_timeout)
{
g_source_remove (manager_kms->handle_hotplug_timeout);
manager_kms->handle_hotplug_timeout = 0;
}
/*
* On a hot-plug event, the EDID of one or more connectors might not yet be
* ready at this point, resulting in invalid configuration potentially being
* applied. Avoid this by first checking whether the EDID is ready at this
* point, or otherwise wait a bit and try again.
*/
manager_kms->read_edid_tries = 0;
if (has_pending_edid_blob (manager_kms))
{
manager_kms->handle_hotplug_timeout =
g_timeout_add (EDID_RETRY_TIMEOUT_MS,
handle_hotplug_event_timeout,
manager);
return;
}
handle_hotplug_event (manager);
}