From: Jim Quinlan <jim2101024@gmail.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Brian Norris <computersforpeace@gmail.com>,
Russell King <rmk+kernel@armlinux.org.uk>,
Robin Murphy <robin.murphy@arm.com>,
Jonas Gorski <jonas.gorski@gmail.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
Linux-MIPS <linux-mips@linux-mips.org>,
linux-pci <linux-pci@vger.kernel.org>,
Kevin Cernekee <cernekee@gmail.com>,
Ralf Baechle <ralf@linux-mips.org>,
bcm-kern
Subject: Re: [PATCH v4 4/8] PCI: brcmstb: Add dma-range mapping for inbound traffic
Date: Mon, 12 Feb 2018 08:39:43 -0500 [thread overview]
Message-ID: <CANCKTBvS8jCgoq4EzBSdXeQ_Hc50+WHfyAoc=H8LJTbF3dCtNA@mail.gmail.com> (raw)
In-Reply-To: <CANCKTBszKRp7gYKE=S3fA0=MoOVFFkO6PgmR476t3HAJ9US2gg@mail.gmail.com>
On Fri, Jan 26, 2018 at 12:46 PM, Jim Quinlan <jim2101024@gmail.com> wrote:
> On Fri, Jan 26, 2018 at 2:53 AM, Christoph Hellwig <hch@lst.de> wrote:
>> On Wed, Jan 24, 2018 at 12:04:58PM -0800, Florian Fainelli wrote:
>>> This looks nicer than the current shape, but this still requires to
>>> register a PCI fixup to override phys_to_dma() and dma_to_phys(), and it
>>> would appear that you have dodged my question about how this is supposed
>>> to fit with an entirely modular PCIe root complex driver? Are you
>>> suggesting that we split the module into a built-in part and a modular part?
>>
>> I don't think entirely modular PCI root bridges should be a focal point
>> for the design. If we happen to support them by other design choices:
>> fine, but they should not be a priority.
>
> I disagree. If there is one common thing our customers request it is
> the ability to remove (or control the insmod of after boot) the pcie
> RC driver. I didn't add this in as a "nice-to-have".
>
>>
>> That being said if we have core dma mapping or PCIe code that has
>> a list of offsets and the root complex only populates them it should
>> work just fine.
>
> I'm looking at arch/arm/include/asm/dma-mapping.h. In addition to
> overriding dma_to_phsy() and phys_to_dma(), it looks like I may have
> to define __arch_pfn_to_dma(), __arch_dma_to_pfn(),
> __arch_dma_to_virt(), __arch_virt_to_dma(). Do you agree or is this
> not necessary? If it is, this seems more intrusive than our
> pcie-brcmstb-dma.c solution which doesn't require tentacles into
> major include files and Kconfigs.
>
> Another issue is that our function wrappers -- depending upon whether
> we are dealing with a pci device or not -- will have to possibly call
> the actual ARM and ARM64 definitions of these functions, which have
> been of course #ifdef'd out. This means that our code must contain
> identical copies of these functions' code and that the code must
> somehow be kept in sync. Do you see a solution to this?
>
> Jim
Cristoph,
Could you please respond to my comments? Even a negative response is
better than none. The problem with doing what you suggested is with
ARM -- ARM64 and MIPS relatively uncomplicated . With ARM, I have to
define the aforementioned functions -- the only way of doing this is
to define arch/arm/mach-bcm/include/mach/memory.h, and for that to be
picked up we no longer can have CONFIG_ARCH_MULTIPLATFORM=y, which is
an unacceptable cost to pay for just an unusual PCIe RC controller.
Regarding my current submission -- you are right, SWIOTLB will not
work for EPs that require it. However, we don't care about these
devices, and can just bailout with EPs when the dma_mask is <=
0xffff_ffff or if swiotlb_force == SWIOTLB_FORCE. Note that this
would only affect PCIe DMA. We also have no plan of using MIPS64.
-- Jim
next prev parent reply other threads:[~2018-02-12 13:39 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-15 23:28 [PATCH v4 0/8] PCI: brcmstb: Add Broadcom Settopbox PCIe support Jim Quinlan
2018-01-15 23:28 ` [PATCH v4 1/8] SOC: brcmstb: add memory API Jim Quinlan
2018-03-09 15:07 ` James Hogan
2018-01-15 23:28 ` [PATCH v4 2/8] dt-bindings: pci: Add DT docs for Brcmstb PCIe device Jim Quinlan
2018-01-19 19:20 ` Rob Herring
[not found] ` <1516058925-46522-1-git-send-email-jim2101024-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-01-15 23:28 ` [PATCH v4 3/8] PCI: brcmstb: Add Broadcom STB PCIe host controller driver Jim Quinlan
2018-01-15 23:28 ` [PATCH v4 4/8] PCI: brcmstb: Add dma-range mapping for inbound traffic Jim Quinlan
2018-01-18 2:15 ` Rob Herring
[not found] ` <CAL_JsqKpWNJXNpKS5qC99N0+H_P37DcRE-rN9HFwT5tVmRFCNw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-01-18 7:31 ` Christoph Hellwig
2018-01-18 15:09 ` Florian Fainelli
[not found] ` <EDAEFB0F-BB7C-444A-B282-F178F5ADFCBF-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-01-18 15:23 ` Christoph Hellwig
2018-01-19 19:47 ` Florian Fainelli
2018-01-23 13:20 ` Christoph Hellwig
2018-01-24 20:04 ` Florian Fainelli
[not found] ` <f746f9d5-b12d-9ffc-83e3-3851b4de6e52-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-01-26 7:53 ` Christoph Hellwig
2018-01-26 17:46 ` Jim Quinlan
2018-02-12 13:39 ` Jim Quinlan [this message]
2018-01-15 23:28 ` [PATCH v4 5/8] PCI/MSI: Enable PCI_MSI_IRQ_DOMAIN support for MIPS Jim Quinlan
2018-01-15 23:28 ` [PATCH v4 6/8] PCI: brcmstb: Add MSI capability Jim Quinlan
2018-01-15 23:28 ` [PATCH v4 7/8] MIPS: BMIPS: Add PCI bindings for 7425, 7435 Jim Quinlan
2018-03-09 14:44 ` James Hogan
2018-01-15 23:28 ` [PATCH v4 8/8] MIPS: BMIPS: Enable PCI Jim Quinlan
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