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From: Christoph Hellwig <hch@lst.de>
To: Marcin Wojtas <mw@semihalf.com>
Cc: "Marek Behún" <kabel@kernel.org>,
	"Russell King (Oracle)" <linux@armlinux.org.uk>,
	pali@kernel.org, "Christoph Hellwig" <hch@lst.de>,
	"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 09:10:00 +0200	[thread overview]
Message-ID: <20221004071000.GA28925@lst.de> (raw)
In-Reply-To: <CAPv3WKcggJ3ki+8DQyA=P=+d714kYxA2-M5xtZf9fEENkk5osQ@mail.gmail.com>

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


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  parent reply	other threads:[~2022-10-04  7:11 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 [this message]
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
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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