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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@ffwll.ch 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@debian.org
commit 8a99914f7b539542622dc571c82d6cd203bddf64 Author: Daniel Vetter daniel.vetter@ffwll.ch 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@alum.mit.edu 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@linux.intel.com Reviewed-by: Maarten Lankhorst maarten.lankhorst@linux.intel.com (v1) Reviewed-by: Nicholas Kazlauskas nicholas.kazlauskas@amd.com (v1) Cc: Michel Dänzer michel@daenzer.net Cc: Alex Deucher alexdeucher@gmail.com Cc: Adam Jackson ajax@redhat.com Acked-by: Adam Jackson ajax@redhat.com Cc: Sean Paul sean@poorly.run Cc: David Airlie airlied@linux.ie Cc: Rob Clark robdclark@gmail.com Acked-by: Rob Clark robdclark@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter daniel.vetter@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20190905185318.31363-1-daniel....
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