diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index 5aa2995273178509b4ad505769c65c0bf746220c..5d14732dc28492b9ecc56baf39285e97aa9e25dd 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -3809,6 +3809,31 @@ void r100_fini(struct radeon_device *rdev)
 	rdev->bios = NULL;
 }
 
+/*
+ * Due to how kexec works, it can leave the hw fully initialised when it
+ * boots the new kernel. However doing our init sequence with the CP and
+ * WB stuff setup causes GPU hangs on the RN50 at least. So at startup
+ * do some quick sanity checks and restore sane values to avoid this
+ * problem.
+ */
+void r100_restore_sanity(struct radeon_device *rdev)
+{
+	u32 tmp;
+
+	tmp = RREG32(RADEON_CP_CSQ_CNTL);
+	if (tmp) {
+		WREG32(RADEON_CP_CSQ_CNTL, 0);
+	}
+	tmp = RREG32(RADEON_CP_RB_CNTL);
+	if (tmp) {
+		WREG32(RADEON_CP_RB_CNTL, 0);
+	}
+	tmp = RREG32(RADEON_SCRATCH_UMSK);
+	if (tmp) {
+		WREG32(RADEON_SCRATCH_UMSK, 0);
+	}
+}
+
 int r100_init(struct radeon_device *rdev)
 {
 	int r;
@@ -3821,6 +3846,8 @@ int r100_init(struct radeon_device *rdev)
 	radeon_scratch_init(rdev);
 	/* Initialize surface registers */
 	radeon_surface_init(rdev);
+	/* sanity check some register to avoid hangs like after kexec */
+	r100_restore_sanity(rdev);
 	/* TODO: disable VGA need to use VGA request */
 	/* BIOS*/
 	if (!radeon_get_bios(rdev)) {
diff --git a/drivers/gpu/drm/radeon/r300.c b/drivers/gpu/drm/radeon/r300.c
index 7e81db5eb8041b1c66afe1ade046724abf235805..3c34da0c899a7600d2309aeb3d9da8f858e94e08 100644
--- a/drivers/gpu/drm/radeon/r300.c
+++ b/drivers/gpu/drm/radeon/r300.c
@@ -1377,6 +1377,8 @@ int r300_init(struct radeon_device *rdev)
 	/* Initialize surface registers */
 	radeon_surface_init(rdev);
 	/* TODO: disable VGA need to use VGA request */
+	/* restore some register to sane defaults */
+	r100_restore_sanity(rdev);
 	/* BIOS*/
 	if (!radeon_get_bios(rdev)) {
 		if (ASIC_IS_AVIVO(rdev))
diff --git a/drivers/gpu/drm/radeon/r420.c b/drivers/gpu/drm/radeon/r420.c
index e6c89142bb4d24323920636cf0e2499c5e17cf59..59f7bccc5be0a291dcf0fcfb9487080ea93d5693 100644
--- a/drivers/gpu/drm/radeon/r420.c
+++ b/drivers/gpu/drm/radeon/r420.c
@@ -343,6 +343,8 @@ int r420_init(struct radeon_device *rdev)
 	/* Initialize surface registers */
 	radeon_surface_init(rdev);
 	/* TODO: disable VGA need to use VGA request */
+	/* restore some register to sane defaults */
+	r100_restore_sanity(rdev);
 	/* BIOS*/
 	if (!radeon_get_bios(rdev)) {
 		if (ASIC_IS_AVIVO(rdev))
diff --git a/drivers/gpu/drm/radeon/r520.c b/drivers/gpu/drm/radeon/r520.c
index 34330df2848329c178a9f2a659d44b0596b0bbaf..213e2e0027a3b63f5364a4570b105940d1fe52c9 100644
--- a/drivers/gpu/drm/radeon/r520.c
+++ b/drivers/gpu/drm/radeon/r520.c
@@ -230,6 +230,8 @@ int r520_init(struct radeon_device *rdev)
 	radeon_scratch_init(rdev);
 	/* Initialize surface registers */
 	radeon_surface_init(rdev);
+	/* restore some register to sane defaults */
+	r100_restore_sanity(rdev);
 	/* TODO: disable VGA need to use VGA request */
 	/* BIOS*/
 	if (!radeon_get_bios(rdev)) {
diff --git a/drivers/gpu/drm/radeon/radeon_asic.h b/drivers/gpu/drm/radeon/radeon_asic.h
index c0bbaa64157a466efb81990431903dc8fbe2dc33..a5aff755f0d2e185dbdd4a1efd541dea5dae78fa 100644
--- a/drivers/gpu/drm/radeon/radeon_asic.h
+++ b/drivers/gpu/drm/radeon/radeon_asic.h
@@ -113,6 +113,7 @@ void r100_wb_fini(struct radeon_device *rdev);
 int r100_wb_init(struct radeon_device *rdev);
 int r100_cp_reset(struct radeon_device *rdev);
 void r100_vga_render_disable(struct radeon_device *rdev);
+void r100_restore_sanity(struct radeon_device *rdev);
 int r100_cs_track_check_pkt3_indx_buffer(struct radeon_cs_parser *p,
 					 struct radeon_cs_packet *pkt,
 					 struct radeon_bo *robj);
diff --git a/drivers/gpu/drm/radeon/rs400.c b/drivers/gpu/drm/radeon/rs400.c
index 9e4240b3bf0bb1ff950b4c74a8e003fc51903e2b..c178481101e9506a2792bd5ca638fda3be59b5e6 100644
--- a/drivers/gpu/drm/radeon/rs400.c
+++ b/drivers/gpu/drm/radeon/rs400.c
@@ -480,6 +480,8 @@ int rs400_init(struct radeon_device *rdev)
 	/* Initialize surface registers */
 	radeon_surface_init(rdev);
 	/* TODO: disable VGA need to use VGA request */
+	/* restore some register to sane defaults */
+	r100_restore_sanity(rdev);
 	/* BIOS*/
 	if (!radeon_get_bios(rdev)) {
 		if (ASIC_IS_AVIVO(rdev))
diff --git a/drivers/gpu/drm/radeon/rs600.c b/drivers/gpu/drm/radeon/rs600.c
index 27d2e706c650258a3c3aeec76dde828ea500b7d0..c5760921d1668db6cc4e64911543fa57c5fdcbe1 100644
--- a/drivers/gpu/drm/radeon/rs600.c
+++ b/drivers/gpu/drm/radeon/rs600.c
@@ -879,6 +879,8 @@ int rs600_init(struct radeon_device *rdev)
 	radeon_scratch_init(rdev);
 	/* Initialize surface registers */
 	radeon_surface_init(rdev);
+	/* restore some register to sane defaults */
+	r100_restore_sanity(rdev);
 	/* BIOS */
 	if (!radeon_get_bios(rdev)) {
 		if (ASIC_IS_AVIVO(rdev))
diff --git a/drivers/gpu/drm/radeon/rs690.c b/drivers/gpu/drm/radeon/rs690.c
index 23676b659e65488260679c8375d8042d8f38e19e..3dde54d57d0916d1571821ee8d3c61e6eab213c9 100644
--- a/drivers/gpu/drm/radeon/rs690.c
+++ b/drivers/gpu/drm/radeon/rs690.c
@@ -707,6 +707,8 @@ int rs690_init(struct radeon_device *rdev)
 	radeon_scratch_init(rdev);
 	/* Initialize surface registers */
 	radeon_surface_init(rdev);
+	/* restore some register to sane defaults */
+	r100_restore_sanity(rdev);
 	/* TODO: disable VGA need to use VGA request */
 	/* BIOS*/
 	if (!radeon_get_bios(rdev)) {
diff --git a/drivers/gpu/drm/radeon/rv515.c b/drivers/gpu/drm/radeon/rv515.c
index 7d9a7b0a180ac7b735702221450e2a9e12be92fe..3f04f735deae802be3af6d0d531caaac945b5323 100644
--- a/drivers/gpu/drm/radeon/rv515.c
+++ b/drivers/gpu/drm/radeon/rv515.c
@@ -468,6 +468,8 @@ int rv515_init(struct radeon_device *rdev)
 	/* Initialize surface registers */
 	radeon_surface_init(rdev);
 	/* TODO: disable VGA need to use VGA request */
+	/* restore some register to sane defaults */
+	r100_restore_sanity(rdev);
 	/* BIOS*/
 	if (!radeon_get_bios(rdev)) {
 		if (ASIC_IS_AVIVO(rdev))