From: Sidong Yang <realwakka@gmail.com>
To: Daniel Vetter <daniel@ffwll.ch>, Melissa Wen <melissa.srw@gmail.com>
Cc: Haneen Mohammed <hamohammed.sa@gmail.com>,
Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>,
David Airlie <airlied@linux.ie>,
Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
kernel-usp@googlegroups.com, Melissa Wen <melissa.srw@gmail.com>
Subject: Re: [PATCH] drm/vkms: add missing drm_crtc_vblank_put to the get/put pair on flush
Date: Tue, 28 Jul 2020 16:16:34 +0000 [thread overview]
Message-ID: <20200728161634.GA6555@realwakka> (raw)
In-Reply-To: <CAKMK7uGQXXDhYGOwYdorKECgNW2Ydq=Mxu_Tm-GrOY8SHftB+g@mail.gmail.com>
On Sun, Jul 26, 2020 at 12:26:08PM +0200, Daniel Vetter wrote:
> On Sat, Jul 25, 2020 at 9:29 PM Melissa Wen <melissa.srw@gmail.com> wrote:
> >
> > On Sat, Jul 25, 2020 at 4:19 PM Melissa Wen <melissa.srw@gmail.com> wrote:
> > >
> > > > No, this very first warning continues (only once) :(
> > > > From here (drm_crtc_vblank_on):
> > > > if (atomic_read(&vblank->refcount) != 0 || drm_vblank_offdelay == 0)
> > > > drm_WARN_ON(dev, drm_vblank_enable(dev, pipe));
> > >
> > > Sorry, not sure when this warning is triggered.
> >
> > Again, I just had to look at the trace:
> > [ 52.299388] drm_get_last_vbltimestamp+0xaa/0xc0 [drm]
> > [ 52.299389] drm_reset_vblank_timestamp+0x5b/0xd0 [drm]
> > [ 52.299389] drm_crtc_vblank_on.cold+0x37/0x103 [drm]
> > [ 52.299390] drm_atomic_helper_commit_modeset_enable
>
> Yeah I think vkms can't generate a reasonable timestamp when the
> hrtimer is off. I thought the warning comes from a different
> callchain, but seems to be a general problem.
>
> I guess in the vkms timestamp function we should check whether the
> timer is running, and if it's not running, then we just grab the
> current time and done.
I tried some test about this scenario that commit_tail calls in sequence disable
- enable - commit.
In a first test. there was a warning and found out that it raised from
vkms_get_vblank_timestamp() the code checking vblank_hrtimer's expire time and
vblank_time. In first run, vblank_time and hrtimer's expire time was both zero.
because vblank wasn't happened yet. this warning wasn't happend since second run
that vblank time was set from first run.
I don't know it's good way to solve the problem. Is there no problem in other
drm modules?
-Sidong
> -Daniel
>
> > >
> > > >
> > > > > But I'm still wondering why after step 3 we don't get -EINVAL from
> > > > > vblank_get() - after vblank_off() vblank->enabled should be false
> > > > > again, getting us back to the same state as after 1. Is that not
> > > > > happening?
> > > >
> > > > Yes (sorry if it got confused), we got -EINVAL after setp 3:
> > > >
> > > > In step 3, at the end of the 2nd running, we have:
> > > > atomic_disable
> > > > --> vblank_off [!vblank->inmodeset + refcount going 0->1 + inmodeset=1]
> > > > and then in next vblank_get: -EINVAL (!vblank->enabled + refcount ends 1)
> > > > as in the first step.
> > > >
> > > > Melissa
> > > >
> > > > > -Daniel
> > > > >
> > > > > >
> > > > > > > >
> > > > > > > > Thanks
> > > > > > > > -Sidong
> > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > > crtc->state->event = NULL;
> > > > > > > > > > > > }
> > > > > > > > > > > >
> > > > > > > > > > > > --
> > > > > > > > > > > > 2.27.0
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > --
> > > > > > > > > > > Daniel Vetter
> > > > > > > > > > > Software Engineer, Intel Corporation
> > > > > > > > > > > http://blog.ffwll.ch
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > --
> > > > > > > > > Daniel Vetter
> > > > > > > > > Software Engineer, Intel Corporation
> > > > > > > > > http://blog.ffwll.ch
> > > > > > > > > _______________________________________________
> > > > > > > > > dri-devel mailing list
> > > > > > > > > dri-devel@lists.freedesktop.org
> > > > > > > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > --
> > > > > > > Daniel Vetter
> > > > > > > Software Engineer, Intel Corporation
> > > > > > > http://blog.ffwll.ch
> > > > >
> > > > >
> > > > >
> > > > > --
> > > > > Daniel Vetter
> > > > > Software Engineer, Intel Corporation
> > > > > http://blog.ffwll.ch
>
>
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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next prev parent reply other threads:[~2020-07-28 16:16 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-22 11:04 [PATCH] drm/vkms: add missing drm_crtc_vblank_put to the get/put pair on flush Melissa Wen
2020-07-22 12:05 ` daniel
2020-07-22 14:06 ` Melissa Wen
2020-07-22 15:17 ` Daniel Vetter
2020-07-25 1:17 ` Sidong Yang
2020-07-25 15:57 ` Daniel Vetter
2020-07-25 17:45 ` Melissa Wen
2020-07-25 18:12 ` Daniel Vetter
2020-07-25 18:49 ` Melissa Wen
2020-07-25 19:19 ` Melissa Wen
2020-07-25 19:29 ` Melissa Wen
2020-07-26 10:26 ` Daniel Vetter
2020-07-28 16:16 ` Sidong Yang [this message]
2020-07-28 21:55 ` daniel
2020-07-29 19:09 ` Melissa Wen
2020-07-29 21:48 ` Daniel Vetter
2020-07-30 10:09 ` Melissa Wen
2020-07-31 9:08 ` daniel
2020-07-31 16:13 ` Sidong Yang
2020-07-31 16:47 ` Melissa Wen
2020-07-31 17:29 ` Leandro Ribeiro
2020-07-31 17:36 ` Leandro Ribeiro
2020-07-31 18:10 ` Leandro Ribeiro
2020-07-31 18:33 ` Daniel Vetter
2020-07-31 18:39 ` Leandro Ribeiro
2020-08-01 16:06 ` Sidong Yang
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