We have two calling contexts for thise function:
- In the crtc helper code itself as part of the ->set_config
implementation. In this calling context all modeset locks are
already held, as they should.
- In drivers not implementing fastboot before the fbdev/fbcon setup
and initialization. This has been added for all drivers in
commit 76a39dbfb2d1bc45219839e5a95d4ceaf6ca114f
Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
Date: Sun Jan 20 23:12:54 2013 +0100
drm/fb-helper: don't disable everything in initial_config
In this calling context we do not hold any modeset locks since the
immediately following call to initialize the fbev emulation grabs
all these locks themselves.
- There are two exceptions to the above rule: shmob doesn't have fbdev
emulation support. I've manually checked the callchain up to the
driver load function and no kms locks are held.
The right fix therefore is to split this helper into an internal and
external version and add the required locking to the function exported
to drivers.
This remedies locking inconsistencies exposed by me adding locking
WARNs as part of the recent kerneldoc abi polishing done in
commit 62ff94a5492175759546f8bc61383189d6b49122
Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
Date: Thu Jan 23 22:18:47 2014 +0100
drm/crtc-helper: remove LOCKING from kerneldoc
and
commit 63951385052f7974155fa38f962f0f4e9847f90a
Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
Date: Thu Jan 23 15:14:15 2014 +0100
drm/doc: Repleace LOCKING kerneldoc sections in drm_modes.c
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
---
drivers/gpu/drm/drm_crtc_helper.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index a85517854073..9d8fb32357c0 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -278,17 +278,7 @@ drm_encoder_disable(struct drm_encoder *encoder)
encoder->bridge->funcs->post_disable(encoder->bridge);
}
-/**
- * drm_helper_disable_unused_functions - disable unused objects
- * @dev: DRM device
- *
- * This function walks through the entire mode setting configuration of @dev. It
- * will remove any crtc links of unused encoders and encoder links of
- * disconnected connectors. Then it will disable all unused encoders and crtcs
- * either by calling their disable callback if available or by calling their
- * dpms callback with DRM_MODE_DPMS_OFF.
- */
-void drm_helper_disable_unused_functions(struct drm_device *dev)
+static void __drm_helper_disable_unused_functions(struct drm_device *dev)
{
struct drm_encoder *encoder;
struct drm_connector *connector;
@@ -323,6 +313,23 @@ void drm_helper_disable_unused_functions(struct drm_device *dev)
}
}
}
+
+/**
+ * drm_helper_disable_unused_functions - disable unused objects
+ * @dev: DRM device
+ *
+ * This function walks through the entire mode setting configuration of @dev. It
+ * will remove any crtc links of unused encoders and encoder links of
+ * disconnected connectors. Then it will disable all unused encoders and crtcs
+ * either by calling their disable callback if available or by calling their
+ * dpms callback with DRM_MODE_DPMS_OFF.
+ */
+void drm_helper_disable_unused_functions(struct drm_device *dev)
+{
+ drm_modeset_lock_all(dev);
+ __drm_helper_disable_unused_functions(dev);
+ drm_modeset_unlock_all(dev);
+}
EXPORT_SYMBOL(drm_helper_disable_unused_functions);
/*
--
1.8.4.rc3
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