From: Christoph Hellwig <hch@lst.de>
To: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Alexandre Torgue <alexandre.torgue@st.com>,
info@metux.net, linux@armlinux.org.uk,
linux-stm32@st-md-mailman.stormreply.com,
Rob Herring <robh+dt@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Maxime Coquelin <mcoquelin.stm32@gmail.com>,
tglx@linutronix.de, dillon min <dillon.minfei@gmail.com>,
Christoph Hellwig <hch@lst.de>,
allison@lohutok.net
Subject: Re: [PATCH 2/2] arm-nommu: Add use_reserved_mem() to check if device support reserved memory
Date: Tue, 9 Jun 2020 19:34:55 +0200 [thread overview]
Message-ID: <20200609173455.GA25467@lst.de> (raw)
In-Reply-To: <b0c85637-4646-614b-d406-49aa72ce52e1@arm.com>
On Tue, Jun 09, 2020 at 05:25:04PM +0100, Vladimir Murzin wrote:
> Even though commit mentions ARM, I do not see how mmap would continue
> to work for NOMMU with dma-direct. ARM NOMMU needs it's own DMA operations
> only in cases where caches are implemented or active, in other cases it
> fully relies on dma-direct.
> It looks to me that we either should provide NOMMU variant for mmap in
> dma/direct or (carefully) fix dma/mapping.
I think dma-direct is the right place, the common helpers in
dma/mapping.c are basically the red headed stepchilds for misc
IOMMU drivers not covered by dma-iommu only.
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next prev parent reply other threads:[~2020-06-09 17:35 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-08 8:30 [PATCH 0/2] Use 'arm_nommu_dma_ops' to handle dma memroy if device offer consistent dma memory region dillon.minfei
2020-06-08 8:30 ` [PATCH 1/2] ARM: dts: stm32: Setup 4M bytes reserved memory for mmap dillon.minfei
2020-06-09 15:58 ` dillon min
2020-06-08 8:30 ` [PATCH 2/2] arm-nommu: Add use_reserved_mem() to check if device support reserved memory dillon.minfei
2020-06-09 14:08 ` Vladimir Murzin
2020-06-09 15:22 ` dillon min
2020-06-09 15:36 ` Christoph Hellwig
2020-06-09 15:43 ` Vladimir Murzin
2020-06-09 16:25 ` Vladimir Murzin
2020-06-09 17:34 ` Christoph Hellwig [this message]
2020-06-10 2:24 ` dillon min
2020-06-10 7:24 ` Christoph Hellwig
2020-06-10 8:19 ` Vladimir Murzin
2020-06-11 15:45 ` Vladimir Murzin
2020-06-12 2:15 ` dillon min
2020-06-09 15:58 ` [PATCH 0/2] Use 'arm_nommu_dma_ops' to handle dma memroy if device offer consistent dma memory region dillon min
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