From: "Marek Behún" <kabel@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Marcin Wojtas <mw@semihalf.com>,
"Russell King (Oracle)" <linux@armlinux.org.uk>,
pali@kernel.org, Robin Murphy <robin.murphy@arm.com>,
Arnd Bergmann <arnd@kernel.org>,
Andre Przywara <andre.przywara@arm.com>,
Marc Zyngier <maz@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Lunn <andrew@lunn.ch>,
Gregory Clement <gregory.clement@bootlin.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
iommu@lists.linux-foundation.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: REGRESSION in 6.0-rc7 caused by patch "ARM/dma-mapping: use dma-direct unconditionally"
Date: Tue, 4 Oct 2022 10:15:02 +0200 [thread overview]
Message-ID: <20221004101502.5cbffc63@thinkpad> (raw)
In-Reply-To: <20221004071000.GA28925@lst.de>
On Tue, 4 Oct 2022 09:10:00 +0200
Christoph Hellwig <hch@lst.de> wrote:
> On Mon, Oct 03, 2022 at 11:30:31PM +0200, Marcin Wojtas wrote:
> > I have one overall concern here. On all kinds of A38x-based boards I
> > worked on, by default, the firmware set all devices (e.g. network,
> > AHCI, XHCI) on MBUS as fully IO cache coherent - it should be
> > reflected in the MVNETA_WIN_BASE(w) registers attribute field. Bits
> > [15:8] should be set to 0x1D (or 0x1E if there is a second DRAM CS
> > used). Can you please try adding 'dma-coherent;' property under the
> > 'internal-regs' node?
>
> Robin mentioned something similar earlier. This almost smalls like
> we somehow manage to mark these device non-coherent by accident now.
>
> The interesting part of the bisected commit is the change to
> mvebu_hwcc_notifier that used to force the DMA OPS to
> arm_coherent_dma_ops, but now just sets the ->dma_coherent flags,
> which seems to get overriden somehow again. Maybe the notifier is
> run before arch_setup_dma_ops, even if that seems odd? As that is
> the only thing I could think of, maybe try this patch:
>
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index 089c9c644cce2..76789650e2596 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -1770,7 +1770,9 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
> const struct iommu_ops *iommu, bool coherent)
> {
> dev->archdata.dma_coherent = coherent;
> - dev->dma_coherent = coherent;
> +
> + if (coherent)
> + dev->dma_coherent = true;
>
> /*
> * Don't override the dma_ops if they have already been set. Ideally
>
Indeed this fixes the issue, and indeed arch_setup_dma_ops is called
later than mvebu_hwcc_notifier.
bash-5.1# dmesg | grep -Ee '(mvebu_hwcc|arch_setup)' | grep ethernet
[ 0.009350] mvebu-coherency: mvebu_hwcc_notifier f1070000.ethernet
[ 0.009434] mvebu-coherency: mvebu_hwcc_notifier f1030000.ethernet
[ 0.009523] mvebu-coherency: mvebu_hwcc_notifier f1034000.ethernet
[ 1.859657] arch_setup_dma_ops f1070000.ethernet coherent=0
[ 1.874852] arch_setup_dma_ops f1030000.ethernet coherent=0
[ 1.889770] arch_setup_dma_ops f1034000.ethernet coherent=0
But mvebu_hwcc_notifier is called even for device not in internal-regs:\
bash-5.1# dmesg | grep -Ee '(mvebu_hwcc|arch_setup)'
[ 0.006475] mvebu-coherency: mvebu_hwcc_notifier pmu
[ 0.006536] mvebu-coherency: mvebu_hwcc_notifier soc
[ 0.007902] mvebu-coherency: mvebu_hwcc_notifier fff00000.bootrom
[ 0.007946] mvebu-coherency: mvebu_hwcc_notifier soc:internal-regs
...
[ 0.010790] mvebu-coherency: mvebu_hwcc_notifier soc:pcie
This probably means that to fix it, we just need to
select OF_DMA_DEFAULT_COHERENT
in
config MACH_MVEBU_V7
?
That way it will work with existing device-trees.
Marek
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next prev parent reply other threads:[~2022-10-04 8:16 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-30 13:10 REGRESSION in 6.0-rc7 caused by patch "ARM/dma-mapping: use dma-direct unconditionally" Marek Behún
2022-09-30 13:46 ` Robin Murphy
2022-09-30 14:52 ` Marek Behún
2022-09-30 15:02 ` Marek Behún
2022-09-30 16:41 ` Robin Murphy
2022-09-30 18:02 ` Marek Behún
2022-10-03 7:21 ` Christoph Hellwig
2022-10-03 7:30 ` Christoph Hellwig
2022-10-03 14:11 ` Russell King (Oracle)
2022-10-03 15:25 ` Marek Behún
2022-10-03 16:09 ` Pali Rohár
2022-10-03 19:04 ` Marek Behún
2022-10-03 19:08 ` Pali Rohár
2022-10-03 21:30 ` Marcin Wojtas
2022-10-03 21:35 ` Pali Rohár
2022-10-03 22:03 ` Marcin Wojtas
2022-10-04 7:10 ` Christoph Hellwig
2022-10-04 8:15 ` Marek Behún [this message]
2022-10-04 8:17 ` [PATCH] ARM: mvebu: select OF_DMA_DEFAULT_COHERENT if MACH_MVEBU_V7 Marek Behún
2022-10-04 8:30 ` Christoph Hellwig
2022-10-04 12:54 ` Marek Behún
2022-10-04 8:30 ` Arnd Bergmann
2022-10-04 9:14 ` Thorsten Leemhuis
2022-10-04 9:22 ` Russell King (Oracle)
2022-10-04 9:56 ` REGRESSION in 6.0-rc7 caused by patch "ARM/dma-mapping: use dma-direct unconditionally" Robin Murphy
2022-10-04 7:25 ` Russell King (Oracle)
2022-10-04 8:30 ` Marcin Wojtas
2022-10-04 9:08 ` Russell King (Oracle)
2022-10-04 12:36 ` Marek Behún
2022-10-04 12:59 ` Marcin Wojtas
2022-10-04 18:51 ` Pali Rohár
2022-10-04 19:35 ` Marcin Wojtas
2022-10-04 8:26 ` Marek Behún
2022-10-04 8:36 ` Marcin Wojtas
2022-10-20 18:22 ` Russell King (Oracle)
2022-10-20 19:10 ` Marek Behún
2022-10-21 16:25 ` Linus Torvalds
2022-10-21 16:30 ` Christoph Hellwig
2022-10-21 18:21 ` Russell King (Oracle)
2022-10-23 11:58 ` Klaus Kudielka
2022-10-03 18:57 ` Marek Behún
2022-10-01 9:31 ` Thorsten Leemhuis
2022-11-04 12:08 ` REGRESSION in 6.0-rc7 caused by patch "ARM/dma-mapping: use dma-direct unconditionally" #forregzbot Thorsten Leemhuis
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