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Date:   Fri, 19 Mar 2021 17:07:53 +0000
From:   Russell King - ARM Linux admin <linux@armlinux.org.uk>
To:     Christoph Hellwig <hch@lst.de>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Jens Axboe <axboe@kernel.dk>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Richard Henderson <rth@twiddle.net>,
        Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
        Matt Turner <mattst88@gmail.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Michael Ellerman <mpe@ellerman.id.au>,
        linux-ide@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 02/10] ARM: disable CONFIG_IDE in footbridge_defconfig
Message-ID: <20210319170753.GV1463@shell.armlinux.org.uk>
References: <20210318045706.200458-1-hch@lst.de>
 <20210318045706.200458-3-hch@lst.de>
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Sender: Russell King - ARM Linux admin <linux@armlinux.org.uk>
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On Thu, Mar 18, 2021 at 05:56:58AM +0100, Christoph Hellwig wrote:
> footbridge_defconfig enables CONFIG_IDE but no actual host controller
> driver, so just drop it.

I have been using the Cypress 82C693 IDE driver on Footbridge for a
CD ROM drive, and I know it doesn't work with the PATA driver - as
I need to disable BM DMA, otherwise the 82C693/DC21285 combination
deadlocks the PCI bus. The PATA driver doesn't support disabling
BM DMA without disabling it for all PATA ports, which is really
annoying for my IT821x card in the same machine.

So, I'm rather stuck using the PATA driver for the HDDs and the
IDE driver for the CD ROM.

That said, a commit a while back "cleaning up" the PCI layer appears
to have totally shafted the 82C693, as the kernel tries to request
IO resources at the legacy IDE addresses against the PCI bus resource
which only covers 0x1000-0xffff. Hence, the 82C693 IDE ports are non-
functional at the moment.

I'm debating about trying to find a fix to the PCI breakage that was
introduced by "ARM: move PCI i/o resource setup into common code".

I hadn't noticed it because I don't use the CD ROM drive very often,
and I don't upgrade the kernel that often either on the machine -
but it has been running 24x7 for almost two decades.

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