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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Alastair D'Silva <alastair@d-silva.org>
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Subject: Re: [PATCH v4 03/25] powerpc/powernv: Map & release OpenCAPI LPC memory
In-Reply-To: <f763d9d8487e77006b233bc16e0883f956850b6c.camel@kernel.crashing.org>
References: <20200327071202.2159885-1-alastair@d-silva.org> <20200327071202.2159885-4-alastair@d-silva.org> <CAPcyv4iGEHJpZctEm+Do1-kOZBUDeKKcREr=BqcK4kCvLWhAQQ@mail.gmail.com> <f763d9d8487e77006b233bc16e0883f956850b6c.camel@kernel.crashing.org>
Date:   Fri, 03 Apr 2020 15:27:46 +1100
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Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:
> On Wed, 2020-04-01 at 01:48 -0700, Dan Williams wrote:
>> > 
>> > +u64 pnv_ocxl_platform_lpc_setup(struct pci_dev *pdev, u64 size)
>> > +{
>> > +       struct pci_controller *hose = pci_bus_to_host(pdev->bus);
>> > +       struct pnv_phb *phb = hose->private_data;
>> 
>> Is calling the local variable 'hose' instead of 'host' on purpose?
>
> Haha that's funny :-)
>
> It's an oooooooold usage that comes iirc from sparc ? or maybe alpha ?

Yeah it was alpha, I found it in the history tree:

  https://github.com/mpe/linux-fullhistory/blob/1928de59ba4209dc5e9f2cef63560c09ba0df73b/arch/alpha/kernel/mcpcia.c

And airlied found an old manual which confirms it:

  The TIOP module interfaces the AlphaServer 8000 system bus to four I/O channels, called "hoses."

  https://www.hpl.hp.com/hpjournal/dtj/vol7num1/vol7num1art4.pdf


So at least now we know where it comes from.

It's also used widely in mips, microblaze, sh and a little bit in drm.

cheers