linux-kernel - Re: [PATCH 5/4] ARM: footbridge: remove custom DMA address handling

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Date:   Thu, 25 Aug 2022 11:35:56 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Christoph Hellwig <hch@....de>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Arnd Bergmann <arnd@...db.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Marc Zyngier <maz@...nel.org>
Subject: Re: [PATCH 5/4] ARM: footbridge: remove custom DMA address handling

On Thu, Aug 25, 2022 at 11:17:52AM +0200, Arnd Bergmann wrote:
> -/*
> - * The footbridge is programmed to expose the system RAM at 0xe0000000.
> - * The requirement is that the RAM isn't placed at bus address 0, which
> - * would clash with VGA cards.
> - */
> -#define BUS_OFFSET		0xe0000000
> -#define __virt_to_bus(x)	((x) + (BUS_OFFSET - PAGE_OFFSET))
> -#define __bus_to_virt(x)	((x) - (BUS_OFFSET - PAGE_OFFSET))

... and this tells you why that is with ISA devices.

So, one hell of a big NAK to this patch, sorry.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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