linux-kernel - [PATCH] drm/nouveau: Set DRIVER_ATOMIC cap earlier to fix debugfs

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Message-Id: <20180723171322.9677-1-lyude@redhat.com>
Date:   Mon, 23 Jul 2018 13:13:20 -0400
From:   Lyude Paul <lyude@...hat.com>
To:     gregkh@...uxfoundation.org
Cc:     bskeggs@...hat.com, stable@...r.kernel.org,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/nouveau: Set DRIVER_ATOMIC cap earlier to fix debugfs

commit eb493fbc150f4a28151ae1ee84f24395989f3600 upstream

Currently nouveau doesn't actually expose the state debugfs file that's
usually provided for any modesetting driver that supports atomic, even
if nouveau is loaded with atomic=1. This is due to the fact that the
standard debugfs files that DRM creates for atomic drivers is called
when drm_get_pci_dev() is called from nouveau_drm.c. This happens well
before we've initialized the display core, which is currently
responsible for setting the DRIVER_ATOMIC cap.

So, move the atomic option into nouveau_drm.c and just add the
DRIVER_ATOMIC cap whenever it's enabled on the kernel commandline. This
shouldn't cause any actual issues, as the atomic ioctl will still fail
as expected even if the display core doesn't disable it until later in
the init sequence. This also provides the added benefit of being able to
use the state debugfs file to check the current display state even if
clients aren't allowed to modify it through anything other than the
legacy ioctls.

Additionally, disable the DRIVER_ATOMIC cap in nv04's display core, as
this was already disabled there previously.

Signed-off-by: Lyude Paul <lyude@...hat.com>
Cc: stable@...r.kernel.org
Signed-off-by: Ben Skeggs <bskeggs@...hat.com>
---
 drivers/gpu/drm/nouveau/dispnv04/disp.c | 3 +++
 drivers/gpu/drm/nouveau/nouveau_drm.c   | 7 +++++++
 drivers/gpu/drm/nouveau/nv50_display.c  | 6 ------
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv04/disp.c b/drivers/gpu/drm/nouveau/dispnv04/disp.c
index 501d2d290e9c..70dce544984e 100644
--- a/drivers/gpu/drm/nouveau/dispnv04/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/disp.c
@@ -55,6 +55,9 @@ nv04_display_create(struct drm_device *dev)
 	nouveau_display(dev)->init = nv04_display_init;
 	nouveau_display(dev)->fini = nv04_display_fini;
 
+	/* Pre-nv50 doesn't support atomic, so don't expose the ioctls */
+	dev->driver->driver_features &= ~DRIVER_ATOMIC;
+
 	nouveau_hw_save_vga_fonts(dev, 1);
 
 	nv04_crtc_create(dev, 0);
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
index bbbf353682e1..21d28e812963 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -79,6 +79,10 @@ 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_param_named(atomic, nouveau_atomic, int, 0400);
+
 MODULE_PARM_DESC(runpm, "disable (0), force enable (1), optimus only default (-1)");
 static int nouveau_runtime_pm = -1;
 module_param_named(runpm, nouveau_runtime_pm, int, 0400);
@@ -501,6 +505,9 @@ static int nouveau_drm_probe(struct pci_dev *pdev,
 
 	pci_set_master(pdev);
 
+	if (nouveau_atomic)
+		driver_pci.driver_features |= DRIVER_ATOMIC;
+
 	ret = drm_get_pci_dev(pdev, pent, &driver_pci);
 	if (ret) {
 		nvkm_device_del(&device);
diff --git a/drivers/gpu/drm/nouveau/nv50_display.c b/drivers/gpu/drm/nouveau/nv50_display.c
index bc5c4f2402b4..abe297fda046 100644
--- a/drivers/gpu/drm/nouveau/nv50_display.c
+++ b/drivers/gpu/drm/nouveau/nv50_display.c
@@ -4441,10 +4441,6 @@ nv50_display_destroy(struct drm_device *dev)
 	kfree(disp);
 }
 
-MODULE_PARM_DESC(atomic, "Expose atomic ioctl (default: disabled)");
-static int nouveau_atomic = 0;
-module_param_named(atomic, nouveau_atomic, int, 0400);
-
 int
 nv50_display_create(struct drm_device *dev)
 {
@@ -4469,8 +4465,6 @@ nv50_display_create(struct drm_device *dev)
 	disp->disp = &nouveau_display(dev)->disp;
 	dev->mode_config.funcs = &nv50_disp_func;
 	dev->driver->driver_features |= DRIVER_PREFER_XBGR_30BPP;
-	if (nouveau_atomic)
-		dev->driver->driver_features |= DRIVER_ATOMIC;
 
 	/* small shared memory area we use for notifiers and semaphores */
 	ret = nouveau_bo_new(&drm->client, 4096, 0x1000, TTM_PL_FLAG_VRAM,
-- 
2.17.1