From: Marcin Wojtas <mw@semihalf.com>
To: mpatocka@redhat.com
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Robin Murphy <robin.murphy@arm.com>,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
Joao Pinto <Joao.Pinto@synopsys.com>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-pci@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
Russell King - ARM Linux <linux@armlinux.org.uk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Matt Sealey <neko@bakuhatsu.net>,
Jingoo Han <jingoohan1@gmail.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: framebuffer corruption due to overlapping stp instructions on arm64
Date: Mon, 6 Aug 2018 15:41:34 +0200 [thread overview]
Message-ID: <CAPv3WKdxwoW5MAOvy6uEBEuMpsigMo98hyO+TpKMsFrKR9oBzg@mail.gmail.com> (raw)
In-Reply-To: <99fff4fe-afa9-f12f-a518-472a9dd1c530@arm.com>
Hi Mikulas,
pon., 6 sie 2018 o 14:42 Robin Murphy <robin.murphy@arm.com> napisał(a):
>
> On 06/08/18 11:25, Mikulas Patocka wrote:
> [...]
> >> None of this explains why some transactions fail to make it across
> >> entirely. The overlapping writes in question write the same data to
> >> the memory locations that are covered by both, and so the ordering in
> >> which the transactions are received should not affect the outcome.
> >
> > You're right that the corruption couldn't be explained just by reordering
> > writes. My hypothesis is that the PCIe controller tries to disambiguate
> > the overlapping writes, but the disambiguation logic was not tested and it
> > is buggy. If there's a barrier between the overlapping writes, the PCIe
> > controller won't see any overlapping writes, so it won't trigger the
> > faulty disambiguation logic and it works.
> >
> > Could the ARM engineers look if there's some chicken bit in Cortex-A72
> > that could insert barriers between non-cached writes automatically?
>
> I don't think there is, and even if there was I imagine it would have a
> pretty hideous effect on non-coherent DMA buffers and the various other
> places in which we have Normal-NC mappings of actual system RAM.
>
> > I observe these kinds of corruptions:
> > - failing to write a few bytes
>
> That could potentially be explained by the reordering/atomicity issues
> Matt mentioned, i.e. the load is observing part of the store, before the
> store has fully completed.
>
> > - writing a few bytes that were written 16 bytes before
> > - writing a few bytes that were written 16 bytes after
>
> Those sound more like the interconnect or root complex ignoring the byte
> strobes on an unaligned burst, of which I think the simplistic view
> would be "it's broken".
>
> FWIW I stuck my old Nvidia 7600GT card in my Arm Juno r2 board (2x
> Cortex-A72), built your test program natively with GCC 8.1.1 at -O2, and
> it's still happily flickering pixels in the corner of the console after
> nearly an hour (in parallel with some iperf3 just to ensure plenty of
> PCIe traffic). I would strongly suspect this issue is particular to
> Armada 8k, so its' probably one for the Marvell folks to take a closer
> look at - I believe some previous interconnect issues on those SoCs were
> actually fixable in firmware.
>
>
On my Macchiato I use GT630 card (nuveau driver) + debian + xfce
desktop and in dual monitor mode, I could run a couple of 1080p
streams. All smooth and I've never noticed any image corruption
whatsoever (I spent a lot of time in front of such setup). Just to be
on a safe side, can you send me a bootlog and your board revision? I'd
like to see your firware version and type.
Thanks,
Marcin
next prev parent reply other threads:[~2018-08-06 13:41 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-02 19:31 framebuffer corruption due to overlapping stp instructions on arm64 Mikulas Patocka
[not found] ` <CAHCPf3tFGqkYEcWNN4LaWThw_rVqT316pzLv6T7RfxwO-eZ0EA@mail.gmail.com>
2018-08-03 6:35 ` Mikulas Patocka
2018-08-03 7:16 ` Ard Biesheuvel
2018-08-03 9:41 ` Will Deacon
2018-08-03 17:09 ` Mikulas Patocka
2018-08-03 17:32 ` Sinan Kaya
2018-08-03 17:33 ` Ard Biesheuvel
2018-08-03 18:25 ` Mikulas Patocka
2018-08-03 20:44 ` Matt Sealey
2018-08-03 21:20 ` Ard Biesheuvel
2018-08-06 10:25 ` Mikulas Patocka
2018-08-06 12:42 ` Robin Murphy
2018-08-06 12:53 ` Ard Biesheuvel
2018-08-06 13:41 ` Marcin Wojtas [this message]
2018-08-06 13:48 ` Ard Biesheuvel
2018-08-06 14:07 ` Marcin Wojtas
2018-08-06 14:13 ` Mikulas Patocka
2018-08-06 15:47 ` Ard Biesheuvel
2018-08-06 17:09 ` Mikulas Patocka
2018-08-06 17:21 ` Ard Biesheuvel
2018-08-06 19:54 ` Mikulas Patocka
2018-08-06 20:11 ` Ard Biesheuvel
2018-08-06 20:31 ` Mikulas Patocka
2018-08-07 16:40 ` Marcin Wojtas
2018-08-07 17:39 ` Mikulas Patocka
2018-08-07 18:07 ` Ard Biesheuvel
2018-08-07 18:17 ` Mikulas Patocka
[not found] ` <CAPv3WKcKoEe=Qysp6Oac2C=G9bUhUQf1twSRCY+_qJ6XEC-iag@mail.gmail.com>
2018-08-08 14:10 ` Mikulas Patocka
2018-08-06 17:13 ` Catalin Marinas
2018-08-06 17:19 ` Mikulas Patocka
2018-08-08 18:31 ` Mikulas Patocka
2018-08-04 13:29 ` Mikulas Patocka
2018-08-08 12:16 ` Catalin Marinas
2018-08-08 13:02 ` David Laight
2018-08-08 13:46 ` Mikulas Patocka
2018-08-08 14:26 ` David Laight
2018-08-08 14:50 ` Catalin Marinas
2018-08-08 16:21 ` Mikulas Patocka
2018-08-08 16:31 ` Arnd Bergmann
2018-08-08 16:43 ` David Laight
2018-08-08 18:56 ` Mikulas Patocka
2018-08-08 18:37 ` Mikulas Patocka
2018-08-08 11:39 ` Catalin Marinas
2018-08-08 14:12 ` Mikulas Patocka
2018-08-08 14:28 ` Catalin Marinas
2018-08-08 18:40 ` Mikulas Patocka
2018-08-08 15:01 ` Richard Earnshaw (lists)
2018-08-08 15:14 ` Catalin Marinas
2018-08-08 16:01 ` Arnd Bergmann
2018-08-08 18:25 ` Mikulas Patocka
2018-08-08 21:51 ` Arnd Bergmann
2018-08-09 15:29 ` Arnd Bergmann
2018-08-03 7:11 ` Andrew Pinski
2018-08-03 7:53 ` Florian Weimer
2018-08-03 9:12 ` Szabolcs Nagy
2018-08-03 9:15 ` Ramana Radhakrishnan
2018-08-03 9:29 ` Ard Biesheuvel
2018-08-03 9:37 ` Ramana Radhakrishnan
2018-08-03 9:42 ` Richard Earnshaw (lists)
2018-08-04 0:58 ` Mikulas Patocka
2018-08-04 1:13 ` Andrew Pinski
2018-08-04 11:04 ` Mikulas Patocka
2018-08-05 18:33 ` Florian Weimer
2018-08-06 8:02 ` Mikulas Patocka
2018-08-06 8:10 ` Ard Biesheuvel
2018-08-06 10:31 ` Mikulas Patocka
2018-08-06 10:37 ` Ard Biesheuvel
2018-08-06 10:42 ` Mikulas Patocka
2018-08-06 10:48 ` Ard Biesheuvel
2018-08-06 12:09 ` Mikulas Patocka
2018-08-06 12:19 ` Ard Biesheuvel
2018-08-06 12:22 ` Ard Biesheuvel
2018-08-07 14:14 ` Mikulas Patocka
2018-08-07 14:40 ` Ard Biesheuvel
2018-08-08 19:15 ` Mikulas Patocka
2018-08-06 11:19 ` Siddhesh Poyarekar
2018-08-06 11:29 ` Ard Biesheuvel
2018-08-06 14:26 ` Tulio Magno Quites Machado Filho
2018-08-05 21:51 ` Pavel Machek
2018-08-06 14:30 ` Mikulas Patocka
2018-08-03 11:24 ` David Laight
2018-08-03 12:04 ` Mikulas Patocka
2018-08-03 13:04 ` David Laight
2018-08-05 14:36 ` Mikulas Patocka
2018-08-06 10:18 ` David Laight
2018-08-07 14:07 ` Mikulas Patocka
2018-08-07 14:33 ` David Laight
2018-08-08 14:21 ` Mikulas Patocka
2018-08-03 13:20 ` Mikulas Patocka
2018-08-03 13:31 ` Mikulas Patocka
2018-08-03 14:17 ` Richard Earnshaw (lists)
2018-08-05 21:36 ` Pavel Machek
2018-08-06 8:04 ` Ramana Radhakrishnan
2018-08-06 8:44 ` Pavel Machek
2018-08-06 9:11 ` Ard Biesheuvel
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