From: Jonathan Gray <jsg@jsg.id.au>
Subject: Re: radeondrm: fix CAFEDEAD failure during boot for old Radeons
To: Ted Bullock <tbullock@comlore.com>
Cc: Mark Kettenis <mark.kettenis@xs4all.nl>, tech@openbsd.org
Date: Fri, 9 Oct 2026 10:55:01 +1100

On Thu, Oct 08, 2026 at 09:02:39AM -0600, Ted Bullock wrote:
> the old radeons i listed in my original mail all report the same issue
> 
> https://marc.info/?l=openbsd-bugs&m=162447131102854
> https://marc.info/?l=openbsd-bugs&m=177938265735653
> https://marc.info/?l=openbsd-misc&m=155873575216626&w=2
> 
> not all of those are sparc 64 there are plenty of old power pc that
> have these exact vintage chips too so id advise something more robust
> than that but i don't have any to test.

Index: sys/dev/pci/drm/radeon/radeon.h
===================================================================
RCS file: /cvs/src/sys/dev/pci/drm/radeon/radeon.h,v
diff -u -p -r1.33 radeon.h
--- sys/dev/pci/drm/radeon/radeon.h	9 Mar 2026 23:58:03 -0000	1.33
+++ sys/dev/pci/drm/radeon/radeon.h	8 Oct 2026 23:22:11 -0000
@@ -2326,6 +2326,7 @@ struct radeon_device {
 	bus_space_tag_t			memt;
 	bus_dma_tag_t			dmat;
 	void				*irqh;
+	bool				dma_limited;
 
 	void				(*switchcb)(void *, int, int);
 	void				*switchcbarg;
Index: sys/dev/pci/drm/radeon/radeon_device.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/drm/radeon/radeon_device.c,v
diff -u -p -r1.34 radeon_device.c
--- sys/dev/pci/drm/radeon/radeon_device.c	5 Oct 2026 08:14:58 -0000	1.34
+++ sys/dev/pci/drm/radeon/radeon_device.c	8 Oct 2026 23:49:59 -0000
@@ -1392,6 +1392,13 @@ int radeon_device_init(struct radeon_dev
 	}
 	rdev->need_swiotlb = drm_need_swiotlb(dma_bits);
 
+	/* disabling sparc64 iommu requires 64 bits */
+#ifdef __sparc64__
+	rdev->dma_limited = true;
+#else
+	rdev->dma_limited = dma_bits <= 32;
+#endif
+
 	/* Registers mapping */
 	/* TODO: block userspace mapping of io register */
 	mtx_init(&rdev->mmio_idx_lock, IPL_TTY);
Index: sys/dev/pci/drm/radeon/radeon_ttm.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/drm/radeon/radeon_ttm.c,v
diff -u -p -r1.28 radeon_ttm.c
--- sys/dev/pci/drm/radeon/radeon_ttm.c	9 Mar 2026 23:58:03 -0000	1.28
+++ sys/dev/pci/drm/radeon/radeon_ttm.c	8 Oct 2026 23:22:11 -0000
@@ -717,7 +717,7 @@ int radeon_ttm_init(struct radeon_device
 			       /*rdev_to_drm(rdev)->anon_inode->i_mapping*/NULL,
 			       rdev_to_drm(rdev)->vma_offset_manager,
 			       rdev->need_swiotlb,
-			       dma_addressing_limited(&rdev->pdev->dev));
+			       rdev->dma_limited);
 #endif
 	if (r) {
 		DRM_ERROR("failed initializing buffer object driver(%d).\n", r);