Some Dell laptops only seem to work with MSIs.  This
looks like a platform/bios bug.
Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=37679
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
            (rdev->pdev->subsystem_device == 0x30c2))
                return true;
 
+       /* Dell RS690 only seems to work with MSIs. */
+       if ((rdev->pdev->device == 0x791f) &&
+           (rdev->pdev->subsystem_vendor == 0x1028) &&
+           (rdev->pdev->subsystem_device == 0x01fd))
+               return true;
+
        if (rdev->flags & RADEON_IS_IGP) {
                /* APUs work fine with MSIs */
                if (rdev->family >= CHIP_PALM)