drm/radeon/kms: fix hardcoded EDID handling

On some servers there is a hardcoded EDID provided
in the vbios so that the driver will always see a
display connected even if something like a KVM
prevents traditional means like DDC or load
detection from working properly.  Also most
server boards with DVI are not actually DVI, but
DVO connected to a virtual KVM service processor.
If we fail to detect a monitor via DDC or load
detection and a hardcoded EDID is available, use
it.

Additionally, when using the hardcoded EDID, use
a copy of it rather than the actual one stored
in the driver as the detect() and get_modes()
functions may free it if DDC is successful.

This fixes the virtual KVM on several internal
servers.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 16 insertions, 5 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_combios.c b/drivers/gpu/drm/radeon/radeon_combios.c
index cf7c8d5b4ec..cf602e2d071 100644
--- a/drivers/gpu/drm/radeon/radeon_combios.c
+++ b/drivers/gpu/drm/radeon/radeon_combios.c
@@ -448,7 +448,7 @@ static uint16_t combios_get_table_offset(struct drm_device *dev,
 
 bool radeon_combios_check_hardcoded_edid(struct radeon_device *rdev)
 {
-	int edid_info;
+	int edid_info, size;
 	struct edid *edid;
 	unsigned char *raw;
 	edid_info = combios_get_table_offset(rdev->ddev, COMBIOS_HARDCODED_EDID_TABLE);
@@ -456,11 +456,12 @@ bool radeon_combios_check_hardcoded_edid(struct radeon_device *rdev)
 		return false;
 
 	raw = rdev->bios + edid_info;
-	edid = kmalloc(EDID_LENGTH * (raw[0x7e] + 1), GFP_KERNEL);
+	size = EDID_LENGTH * (raw[0x7e] + 1);
+	edid = kmalloc(size, GFP_KERNEL);
 	if (edid == NULL)
 		return false;
 
-	memcpy((unsigned char *)edid, raw, EDID_LENGTH * (raw[0x7e] + 1));
+	memcpy((unsigned char *)edid, raw, size);
 
 	if (!drm_edid_is_valid(edid)) {
 		kfree(edid);
@@ -468,6 +469,7 @@ bool radeon_combios_check_hardcoded_edid(struct radeon_device *rdev)
 	}
 
 	rdev->mode_info.bios_hardcoded_edid = edid;
+	rdev->mode_info.bios_hardcoded_edid_size = size;
 	return true;
 }
 
@@ -475,8 +477,17 @@ bool radeon_combios_check_hardcoded_edid(struct radeon_device *rdev)
 struct edid *
 radeon_bios_get_hardcoded_edid(struct radeon_device *rdev)
 {
-	if (rdev->mode_info.bios_hardcoded_edid)
-		return rdev->mode_info.bios_hardcoded_edid;
+	struct edid *edid;
+
+	if (rdev->mode_info.bios_hardcoded_edid) {
+		edid = kmalloc(rdev->mode_info.bios_hardcoded_edid_size, GFP_KERNEL);
+		if (edid) {
+			memcpy((unsigned char *)edid,
+			       (unsigned char *)rdev->mode_info.bios_hardcoded_edid,
+			       rdev->mode_info.bios_hardcoded_edid_size);
+			return edid;
+		}
+	}
 	return NULL;
 }