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: [PATCH] ARM: mvebu: select OF_DMA_DEFAULT_COHERENT if MACH_MVEBU_V7
Date: Tue, 4 Oct 2022 14:54:34 +0200 [thread overview]
Message-ID: <20221004145434.74bb0413@thinkpad> (raw)
In-Reply-To: <20221004083010.GA2312@lst.de>
On Tue, 4 Oct 2022 10:30:10 +0200
Christoph Hellwig <hch@lst.de> wrote:
> On Tue, Oct 04, 2022 at 10:17:23AM +0200, Marek Behún wrote:
> > Commit ae626eb97376 ("ARM/dma-mapping: use dma-direct unconditionally")
> > caused a regression on the mvebu platform, wherein devices that are
> > dma-coherent are marked as dma-noncoherent, because although
> > mvebu_hwcc_notifier() after that commit still marks then as coherent,
> > the arm_coherent_dma_ops() function, which is called later, overwrites
> > this setting, since it is being called from drivers/of/device.c with
> > coherency parameter determined by of_dma_is_coherent(), and the
> > device-trees do not declare the 'dma-coherent' property.
> >
> > Fix this by defaulting to dma-coherent for this platform in the
> > of_dma_is_coherent() function, if neither dma-coherent nor
> > dma-noncoherent is declared.
>
> Can't mvebu be part of multi-platform builds that would be broken by
> this change?
OK, if selecting that isn't possible, then my opinion is that this
should be handled by OF drivers. There is a precedent for this,
drivers/of/address.c has function of_empty_ranges_quirk().
So maybe something like
of_dma_coherency_quirk(),
which will be called from of_dma_is_coherent() ?
> Also if we do this, shouldn't we also remove the notifier that set
> ->dma_coherent?
Yes, the notifier should go away, IMO.
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next prev parent reply other threads:[~2022-10-04 12:56 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
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 [this message]
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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