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Date:   Thu, 11 May 2023 12:36:36 +0200
From:   Petr =?UTF-8?B?VGVzYcWZw61r?= <petr@tesarici.cz>
To:     Juerg Haefliger <juergh@proton.me>
Cc:     Petr Tesarik <petrtesarik@huaweicloud.com>,
        Christoph Hellwig <hch@lst.de>,
        Jonathan Corbet <corbet@lwn.net>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Borislav Petkov <bp@suse.de>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Kim Phillips <kim.phillips@amd.com>,
        "Steven Rostedt (Google)" <rostedt@goodmis.org>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:DMA MAPPING HELPERS" <iommu@lists.linux.dev>,
        Roberto Sassu <roberto.sassu@huawei.com>,
        Alexander Graf <graf@amazon.com>
Subject: Re: [RFC v1 3/4] swiotlb: Allow dynamic allocation of bounce
 buffers
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On Thu, 06 Apr 2023 11:44:55 +0000
Juerg Haefliger <juergh@proton.me> wrote:

> On Fri, 31 Mar 2023 11:00:43 +0200
> Petr Tesa=C5=99=C3=ADk <petr@tesarici.cz> wrote:
>=20
> > Hi Juerg,
> >
> > On Fri, 31 Mar 2023 07:26:09 +0000
> > Juerg Haefliger <juergh@proton.me> wrote:
> > =20
> > > On Tue, 28 Mar 2023 09:54:35 +0200
> > > Petr Tesarik <petrtesarik@huaweicloud.com> wrote:
> > >
> > >[...] =20
> > > > Anyway, I suspected that the buffers need not be imported into the =
vc4
> > > > driver (also hinted by Eric Anholt in a 2018 blog post [1]), and it
> > > > seems I was right. I encountered the issue with Ubuntu 22.10; I
> > > > installed latest openSUSE Tumbleweed yesterday, and I was not able =
to
> > > > reproduce the issue there, most likely because the Mesa drivers have
> > > > been fixed meanwhile. This makes the specific case of the Raspberry=
 Pi 4
> > > > drivers moot. The issue may still affect other combinations of driv=
ers,
> > > > but I don't have any other real-world example ATM. =20
> > >
> > > I'm only seeing this problem with Wayland, no issue when switching Ub=
untu to
> > > X. It seems Tumbleweed is using X by default. =20
> >
> > I know; I was the team lead of SUSE low-level graphics engineers until
> > end of last year... I have just double-checked, but this output of
> > wayland-info in the GNOME session accessed over RDP is quite convincing=
: =20
>=20
> It sure is but how did you get that??

I'm sorry for late reply.

Yes, the default is GNOME on X.org, but you can change it on the GDM
login screen. After choosing your account, a settings gear icon appears
in the lower right corner. Click on it and choose GNOME. That starts a
Wayland session.

HTH
Petr T