From 66aa6962ff520804f9874e57ea97995153f499d8 Mon Sep 17 00:00:00 2001 From: Tormod Volden Date: Mon, 30 May 2011 19:45:43 +0000 Subject: [PATCH] drm: Compare only lower 32 bits of framebuffer map offsets Drivers using multiple framebuffers got broken by commit 41c2e75e60200a860a74b7c84a6375c105e7437f which ignored the framebuffer (or register) map offset when looking for existing maps. The rationale was that the kernel-userspace ABI is fixed at a 32-bit offset, so the real offsets could not always be handed over for comparison. Instead of ignoring the offset we will compare the lower 32 bit. Drivers using multiple framebuffers should just make sure that the lower 32 bit are different. The existing drivers in question are practically limited to 32-bit systems so that should be fine for them. It is assumed that current drivers always specify a correct framebuffer map offset, even if this offset was ignored since above commit. So this patch should not change anything for drivers using only one framebuffer. Drivers needing multiple framebuffers with 64-bit map offsets will need to cook up something, for instance keeping an ID in the lower bit which is to be aligned away when it comes to using the offset. All of above applies to _DRM_REGISTERS as well. Signed-off-by: Tormod Volden Signed-off-by: Dave Airlie --- drivers/gpu/drm/drm_bufs.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/drm_bufs.c b/drivers/gpu/drm/drm_bufs.c index e1bd713d91a2..61e1ef90d4e5 100644 --- a/drivers/gpu/drm/drm_bufs.c +++ b/drivers/gpu/drm/drm_bufs.c @@ -46,10 +46,11 @@ static struct drm_map_list *drm_find_matching_map(struct drm_device *dev, list_for_each_entry(entry, &dev->maplist, head) { /* * Because the kernel-userspace ABI is fixed at a 32-bit offset - * while PCI resources may live above that, we ignore the map - * offset for maps of type _DRM_FRAMEBUFFER or _DRM_REGISTERS. - * It is assumed that each driver will have only one resource of - * each type. + * while PCI resources may live above that, we only compare the + * lower 32 bits of the map offset for maps of type + * _DRM_FRAMEBUFFER or _DRM_REGISTERS. + * It is assumed that if a driver have more than one resource + * of each type, the lower 32 bits are different. */ if (!entry->map || map->type != entry->map->type || @@ -59,9 +60,12 @@ static struct drm_map_list *drm_find_matching_map(struct drm_device *dev, case _DRM_SHM: if (map->flags != _DRM_CONTAINS_LOCK) break; + return entry; case _DRM_REGISTERS: case _DRM_FRAME_BUFFER: - return entry; + if ((entry->map->offset & 0xffffffff) == + (map->offset & 0xffffffff)) + return entry; default: /* Make gcc happy */ ; } -- 2.20.1