From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Arnd Bergmann <arnd@arndb.de>,
Linus Walleij <linus.walleij@linaro.org>,
Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH 5/4] ARM: footbridge: remove custom DMA address handling
Date: Thu, 25 Aug 2022 11:34:12 +0100 [thread overview]
Message-ID: <YwdQJDMExcm4n0vQ@shell.armlinux.org.uk> (raw)
In-Reply-To: <20220825091752.3535657-1-arnd@kernel.org>
On Thu, Aug 25, 2022 at 11:17:52AM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> Footbridge is the last Arm platform that has its own
> __virt_to_bus()/__bus_to_virt()/phys_to_dma()/dma_to_phys() abstraction,
> but this is just a simple offset now.
>
> For ISA DMA (floppy etc), the offset is actually zero, so the special
> hack to subtract the bus offset can be removed from common code.
No, the offset is definitely not zero for ISA devices. ISA devices have
the same view of system memory as PCI devices, since ISA devices go
through a southbridge and on to the PCI bus. So their view of the system
is exactly the same as any other PCI device.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2022-08-25 10:37 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-18 21:15 [PATCH 0/4] ARM: footbridge: cleanups Arnd Bergmann
2022-08-18 21:15 ` [PATCH 1/4] ARM: footbridge: remove addin mode Arnd Bergmann
2022-08-21 5:53 ` Christoph Hellwig
2022-08-24 10:33 ` Arnd Bergmann
2022-08-25 9:17 ` [PATCH 5/4] ARM: footbridge: remove custom DMA address handling Arnd Bergmann
2022-08-25 10:34 ` Russell King (Oracle) [this message]
2022-08-25 10:35 ` Russell King (Oracle)
2022-08-25 17:17 ` Arnd Bergmann
2022-08-25 20:15 ` [PATCH v2 " Arnd Bergmann
2022-08-30 12:21 ` Robin Murphy
2022-08-18 21:15 ` [PATCH 2/4] ARM: footbridge: remove leftover from personal-server Arnd Bergmann
2022-08-21 5:55 ` Christoph Hellwig
2022-08-24 10:37 ` Arnd Bergmann
2022-08-24 10:47 ` Russell King (Oracle)
2022-08-18 21:15 ` [PATCH 3/4] ARM: footbridge: move isa-dma support into footbridge Arnd Bergmann
2022-08-21 5:56 ` Christoph Hellwig
2022-08-18 21:15 ` [PATCH 4/4] ARM: footbridge: limit CONFIG_ISA to CATS Arnd Bergmann
2022-09-04 11:43 ` [PATCH 0/4] ARM: footbridge: cleanups Marc Zyngier
2022-09-04 12:09 ` Russell King (Oracle)
2022-09-04 16:10 ` Marc Zyngier
2022-09-04 21:47 ` Arnd Bergmann
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