This addresses <http://bugzilla.kernel.org/show_bug.cgi?id=15021>.
DRM drivers may fail to probe their devices when the associated AGP
GART does not yet have a driver, so we reprobe unbound VGA devices
when a GART device is added.
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
This is intended to address the dependency problem highlighted in the
above bug report. That specific bug can be fixed by adding a module
dependency from i915 to intel_agp, but in general there is no fixed
relationship betweem DRM and GART drivers.
There is a narrow race between the check for a current driver binding
and the call to device_reprobe(). This could be closed by adding a
variant on device_attach() and device_reprobe() that is a no-op for
bound devices.
Ben.
drivers/char/agp/backend.c | 20 ++++++++++++++++++++
1 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/drivers/char/agp/backend.c b/drivers/char/agp/backend.c
index c3ab46d..f9680bf 100644
--- a/drivers/char/agp/backend.c
+++ b/drivers/char/agp/backend.c
@@ -36,6 +36,7 @@
#include <linux/agp_backend.h>
#include <linux/agpgart.h>
#include <linux/vmalloc.h>
+#include <linux/workqueue.h>
#include <asm/io.h>
#include "agp.h"
@@ -281,6 +282,24 @@ void agp_put_bridge(struct agp_bridge_data *bridge)
EXPORT_SYMBOL(agp_put_bridge);
+/*
+ * DRM drivers may fail to probe their devices when the associated AGP
+ * GART does not yet have a driver, so we reprobe unbound VGA devices
+ * when a GART device is added. This problem applies not only to true
+ * AGP devices which would be children of the affected bridge, but
+ * also to PCI Express devices that may be siblings of the GART
+ * device. Therefore iterate over all PCI VGA devices.
+ */
+static void agp_probe_video(struct work_struct *work)
+{
+ struct pci_dev *pdev = NULL;
+
+ while ((pdev = pci_get_class(0x030000, pdev)) != NULL) {
+ if (!pdev->dev.driver && device_reprobe(&pdev->dev))
+ pr_err(PFX "failed to reprobe %s\n", pci_name(pdev));
+}
+static DECLARE_WORK(agp_probe_video_work, agp_probe_video);
+
int agp_add_bridge(struct agp_bridge_data *bridge)
{
int error;
@@ -324,6 +343,7 @@ int agp_add_bridge(struct agp_bridge_data *bridge)
}
list_add(&bridge->list, &agp_bridges);
+ schedule_work(&agp_probe_video_work);
return 0;
frontend_err:
--
1.6.6.2
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