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On Fri, 2020-05-08 at 11:54 +0200, Greg KH wrote:
> > Hi Daniel and Greg (especially). It seems that this patch was never
> > applied to
> > stable, maybe it fell through the cracks?
>
> What patch is "this patch"?
Sorry, the patch was in the mail I was replying to:
commit 26b1d3b527e7bf3e24b814d617866ac5199ce68d
Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
Date: Thu Sep 5 20:53:18 2019 +0200
drm/atomic: Take the atomic toys away from X
>
> > It doesn't apply as-is in 4.19 branch but a small change in the context
> > makes
> > it apply. I'm experiencing issues with lightdm and vt-switch in Debian
> > Buster
> > (which has a 4.19 kernel) so I'd appreciate if the patch was included in
> > at
> > least that release.
>
> What is the git commit id of the patch in Linus's tree? If you have a
> working backport, that makes it much easier than hoping I can fix it
> up...
The commit id is in Linus tree is 26b1d3b527e7bf3e24b814d617866ac5199ce68d. To
apply properly 69fdf4206a8ba91a277b3d50a3a05b71247635b2 would need to be
cherry-picked as well but it wasn't marked for stable so I didn't bother and
only fixed the context. Here's the backport to 4.19, compile and runtime
tested. It does fix the issue for me (like it did on mainline).
So I guess
Tested-By: Yves-Alexis Perez <corsac@xxxxxxxxxx>
commit 8a99914f7b539542622dc571c82d6cd203bddf64
Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
Date: Thu Sep 5 20:53:18 2019 +0200
drm/atomic: Take the atomic toys away from X
The -modesetting ddx has a totally broken idea of how atomic works:
- doesn't disable old connectors, assuming they get auto-disable like
with the legacy setcrtc
- assumes ASYNC_FLIP is wired through for the atomic ioctl
- not a single call to TEST_ONLY
Iow the implementation is a 1:1 translation of legacy ioctls to
atomic, which is a) broken b) pointless.
We already have bugs in both i915 and amdgpu-DC where this prevents us
from enabling neat features.
If anyone ever cares about atomic in X we can easily add a new atomic
level (req->value == 2) for X to get back the shiny toys.
Since these broken versions of -modesetting have been shipping,
there's really no other way to get out of this bind.
v2:
- add an informational dmesg output (Rob, Ajax)
- reorder after the DRIVER_ATOMIC check to avoid useless noise (Ilia)
- allow req->value > 2 so that X can do another attempt at atomic in
the future
v3: Go with paranoid, insist that the X should be first (suggested by
Rob)
Cc: Ilia Mirkin <imirkin@xxxxxxxxxxxx>
References: https://gitlab.freedesktop.org/xorg/xserver/issues/629
References: https://gitlab.freedesktop.org/xorg/xserver/merge_requests/180
References: abbc0697d5fb ("drm/fb: revert the i915 Actually configure
untiled displays from master")
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> (v1)
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx> (v1)
Cc: Michel Dänzer <michel@xxxxxxxxxxx>
Cc: Alex Deucher <alexdeucher@xxxxxxxxx>
Cc: Adam Jackson <ajax@xxxxxxxxxx>
Acked-by: Adam Jackson <ajax@xxxxxxxxxx>
Cc: Sean Paul <sean@xxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Rob Clark <robdclark@xxxxxxxxx>
Acked-by: Rob Clark <robdclark@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Link:
https://patchwork.freedesktop.org/patch/msgid/20190905185318.31363-1-daniel.vetter@xxxxxxxx
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index ba129b64b61f..b92682f037b2 100644
- --- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -321,7 +321,12 @@ drm_setclientcap(struct drm_device *dev, void *data,
struct drm_file *file_priv)
case DRM_CLIENT_CAP_ATOMIC:
if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
return -EINVAL;
- - if (req->value > 1)
+ /* The modesetting DDX has a totally broken idea of atomic. */
+ if (current->comm[0] == 'X' && req->value == 1) {
+ pr_info("broken atomic modeset userspace detected,
disabling atomic\n");
+ return -EOPNOTSUPP;
+ }
+ if (req->value > 2)
return -EINVAL;
file_priv->atomic = req->value;
file_priv->universal_planes = req->value;
- --
Yves-Alexis
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