From: Arnd Bergmann <arnd@arndb.de>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: John Garry <john.garry@huawei.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
linux-pci <linux-pci@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Will Deacon <will.deacon@arm.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Linuxarm <linuxarm@huawei.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>
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
next prev parent reply other threads:[~2019-06-13 16:34 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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