From: Arnd Bergmann <arnd@arndb.de>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
John Garry <john.garry@huawei.com>,
Will Deacon <will.deacon@arm.com>, Linuxarm <linuxarm@huawei.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-pci <linux-pci@vger.kernel.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v4 2/3] lib: logic_pio: Reject accesses to unregistered CPU MMIO regions
Date: Thu, 13 Jun 2019 09:47:51 +0200 [thread overview]
Message-ID: <CAK8P3a0C010LEs3HmyQKHWx4EVpVH1NUtFwYkoF16syFQ9hd8w@mail.gmail.com> (raw)
In-Reply-To: <20190613032034.GE13533@google.com>
On Thu, Jun 13, 2019 at 5:20 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Tue, Jun 11, 2019 at 10:12:53PM +0800, John Garry wrote:
> > Currently when accessing logical indirect PIO addresses in
> > logic_{in, out}{,s}, we first ensure that the region is registered.
>
> I think logic_pio is specifically concerned with I/O port space, so
> it's a little bit unfortunate that we named this "PIO".
>
> PIO is a general term for "Programmed I/O", which just means the CPU
> is involved in each transfer, as opposed to DMA. The transfers can be
> to either MMIO or I/O port space.
>
> So this ends up being a little confusing because I think you mean
> "Port I/O", not "Programmed I/O".
I think the terms that John uses are more common: I would also
assume that "PIO" (regardless of whether you expand it as Port
or Programmed I/O) refers only to inb/outb and PCI/ISA/LPC
I/O space, and is distinct from "MMIO", which refers to the readl/writel
accessors and PCI memory space.
That is consistent with the usage across at least the x86, powerpc
and ia64 architectures when they refer to PIO.
Arnd
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next prev parent reply other threads:[~2019-06-13 7:48 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-11 14:12 [PATCH v4 0/3] Fix ARM64 crash for accessing unmapped IO port regions John Garry
2019-06-11 14:12 ` [PATCH v4 1/3] lib: logic_pio: Use logical PIO low-level accessors for !CONFIG_INDIRECT_PIO John Garry
2019-06-13 2:39 ` Bjorn Helgaas
2019-06-13 9:39 ` John Garry
2019-06-13 20:09 ` Bjorn Helgaas
2019-06-14 9:02 ` John Garry
2019-06-14 11:50 ` Bjorn Helgaas
2019-06-14 12:22 ` John Garry
2019-06-13 13:58 ` Bjorn Helgaas
2019-06-13 15:21 ` John Garry
2019-06-11 14:12 ` [PATCH v4 2/3] lib: logic_pio: Reject accesses to unregistered CPU MMIO regions John Garry
2019-06-13 3:20 ` Bjorn Helgaas
2019-06-13 7:47 ` Arnd Bergmann [this message]
2019-06-13 10:17 ` John Garry
2019-06-13 13:46 ` Bjorn Helgaas
2019-06-13 14:09 ` John Garry
2019-06-11 14:12 ` [PATCH v4 3/3] lib: logic_pio: Fix up a print John Garry
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