[PATCH 4/4] drm/nouveau/kms/nv50-: Enable atomic modesetting by default

[Lyude Paul <lyude@redhat.com>]

Nouveau is one of the very few modern hardware drivers in the kernel that
doesn't have atomic modesetting enabled by default, in part because when it
was originally written by Ben there wasn't much in the way of good atomic
modesetting clients to actually test things out with.

Nowadays however, atomic modesetting is very much the norm - and support in
userspace for non-atomic drivers is starting to bitrot a bit - leading to
its own set of issues. At the same time, many of those issues are fixed by
just turning on atomic in nouveau. Plus, I've been running nouveau with
atomic modesetting on by default for most of the machines I work on, and
I've already fixed quite a number of issues to the point where things seem
quite stable (excluding a single screen flashing bug on my desktop, which I
am not particularly convinced has anything to do with atomic modesetting).

Now that we've protected against breaking things for chipsets where atomic
isn't supported (<nv50) - let's enable it by default on generations of
hardware that support it. We'll leave the module parameter around for the
time being, as turning it off may be helpful in the possibility that we hit
regressions.

Signed-off-by: Lyude Paul <lyude@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_drm.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
index b959d79f7e1c7..5580ac9c782ba 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -103,8 +103,9 @@ MODULE_PARM_DESC(modeset, "enable driver (default: auto, "
 int nouveau_modeset = -1;
 module_param_named(modeset, nouveau_modeset, int, 0400);
 
-MODULE_PARM_DESC(atomic, "Expose atomic ioctl (default: disabled)");
-static int nouveau_atomic = 0;
+MODULE_PARM_DESC(atomic, "Expose atomic ioctl (default: auto, "
+			 "0 = disabled, 1 = enabled)");
+static int nouveau_atomic = -1;
 module_param_named(atomic, nouveau_atomic, int, 0400);
 
 MODULE_PARM_DESC(runpm, "disable (0), force enable (1), optimus only default (-1)");
@@ -770,10 +771,10 @@ nouveau_drm_device_new(struct drm_driver *drm_driver, struct device *parent,
 		goto done;
 	}
 
-	if (nouveau_atomic) {
+	if (nouveau_atomic != 0) {
 		if (drm->device.info.chipset >= NV_DEVICE_INFO_V0_TESLA)
 			driver_pci.driver_features |= DRIVER_ATOMIC;
-		else
+		else if (nouveau_atomic == 1)
 			NV_WARN(drm, "Atomic modesetting not supported (needs nv50+)\n");
 	}
 
-- 
2.55.0