From: catalin.marinas@arm•com (Catalin Marinas)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v7 1/6] pci: Introduce pci_register_io_range() helper function.
Date: Thu, 26 Jun 2014 09:59:26 +0100 [thread overview]
Message-ID: <20140626085926.GB11244@arm.com> (raw)
In-Reply-To: <CAErSpo4iEV6khP63ZTF+YUTKi9WLFXzMv13nxw15y3qDg15Ztg@mail.gmail.com>
(sorry for replying to a months old thread)
On Mon, Apr 07, 2014 at 06:58:24PM +0100, Bjorn Helgaas wrote:
> On Mon, Apr 7, 2014 at 5:36 AM, Arnd Bergmann <arnd@arndb•de> wrote:
>
> > I think migrating other architectures to use the same code should be
> > a separate effort from adding a generic implementation that can be
> > used by arm64. It's probably a good idea to have patches to convert
> > arm32 and/or microblaze.
>
> Let me reiterate that I am 100% in favor of replacing arch-specific
> code with more generic implementations.
>
> However, I am not 100% in favor of doing it as separate efforts
> (although maybe I could be convinced). The reasons I hesitate are
> that (1) if only one architecture uses a new "generic" implementation,
> we really don't know whether it is generic enough, (2) until I see the
> patches to convert other architectures, I have to assume that I'm the
> one who will write them, and (3) as soon as we add the code to
> drivers/pci, it becomes partly my headache to maintain it, even if
> only one arch benefits from it.
I agree and understand your point.
> Please don't think I'm questioning anyone's intent or good will. It's
> just that I understand the business pressures, and I know how hard it
> can be to justify this sort of work to one's management, especially
> after the immediate problem has been solved.
But, unfortunately, that's something we failed to address in reasonable
time (even though I was one of the proponents of the generic PCIe
implementation). This work is very likely to slip further into the late
part of this year and I am aware that several ARM partners are blocked
on the (upstream) availability of PCIe support for the arm64 kernel.
Although a bit late, I'm raising this now and hopefully we'll come to a
conclusion soon. Delaying arm64 PCIe support even further is not a real
option, which leaves us with:
1. Someone else (with enough PCIe knowledge) volunteering to take over
soon or
2. Dropping Liviu's work and going for an arm64-specific implementation
(most likely based on the arm32 implementation, see below)
First option is ideal but there is work to do as laid out by Arnd here:
http://article.gmane.org/gmane.linux.kernel/1679304
The latest patches from Liviu are here (they only target arm64 and there
are additional comments to be addressed from the above thread):
http://linux-arm.org/git?p=linux-ld.git;a=shortlog;h=refs/heads/for-upstream/pci-next
The main reason for the second option is timing. We could temporarily
move Liviu's code under arch/arm64 with the hope that we generalise it
later. However, the risk is even higher that once the code is in
mainline, the generic implementation won't happen. In which case, I
don't see much point in departing from the arm32 PCI API, making bios32
clone the best second option.
For the alternative implementation above, we already have a heavily cut
down version of the arm32 PCI support but only tested in a virtual
environment so far:
https://git.kernel.org/cgit/linux/kernel/git/will/linux.git/log/?h=pci/bios32
In conclusion, unless someone volunteers for the first option fairly
soon, we'll post the alternative patches for review and take it from
there.
Thanks.
--
Catalin
next prev parent reply other threads:[~2014-06-26 8:59 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-14 15:34 [PATCH v7 0/6] Support for creating generic host_bridge from device tree Liviu Dudau
2014-03-14 15:34 ` [PATCH v7 1/6] pci: Introduce pci_register_io_range() helper function Liviu Dudau
2014-04-05 0:19 ` Bjorn Helgaas
2014-04-06 9:49 ` Benjamin Herrenschmidt
2014-04-07 8:35 ` Liviu Dudau
2014-04-07 9:13 ` Benjamin Herrenschmidt
2014-04-07 11:16 ` Arnd Bergmann
2014-04-07 8:31 ` Liviu Dudau
2014-04-07 11:36 ` Arnd Bergmann
2014-04-07 13:42 ` Liviu Dudau
2014-04-07 17:58 ` Bjorn Helgaas
2014-04-08 9:50 ` Liviu Dudau
2014-04-08 10:22 ` Arnd Bergmann
2014-04-08 16:54 ` Bjorn Helgaas
2014-06-26 8:59 ` Catalin Marinas [this message]
2014-06-26 9:30 ` Liviu Dudau
2014-06-26 14:11 ` Catalin Marinas
2014-06-26 14:14 ` Will Deacon
2014-06-27 0:44 ` Rob Herring
2014-06-27 11:03 ` Arnd Bergmann
2014-06-27 12:49 ` Will Deacon
2014-06-27 13:16 ` Arnd Bergmann
2014-06-27 13:38 ` Catalin Marinas
2014-06-27 16:15 ` Rob Herring
2014-06-30 10:17 ` Will Deacon
2014-06-27 14:14 ` Catalin Marinas
2014-06-27 14:55 ` Bjorn Helgaas
2014-06-27 15:18 ` Liviu Dudau
2014-04-07 23:21 ` Bjorn Helgaas
2014-04-08 7:12 ` Arnd Bergmann
2014-04-08 9:49 ` Liviu Dudau
2014-04-08 10:11 ` Arnd Bergmann
2014-04-08 16:48 ` Bjorn Helgaas
2014-03-14 15:34 ` [PATCH v7 2/6] pci: OF: Fix the conversion of IO ranges into IO resources Liviu Dudau
2014-03-14 17:05 ` Arnd Bergmann
2014-03-14 17:19 ` Liviu Dudau
2014-03-14 18:46 ` Arnd Bergmann
2014-03-14 19:00 ` Liviu Dudau
2014-03-14 19:16 ` Arnd Bergmann
2014-03-17 13:41 ` Liviu Dudau
2014-03-14 15:34 ` [PATCH v7 3/6] pci: Create pci_host_bridge before its associated bus in pci_create_root_bus Liviu Dudau
2014-03-14 15:34 ` [PATCH v7 4/6] pci: Introduce a domain number for pci_host_bridge Liviu Dudau
2014-04-05 0:00 ` Bjorn Helgaas
2014-04-07 8:46 ` Liviu Dudau
2014-04-07 9:14 ` Benjamin Herrenschmidt
2014-04-07 10:07 ` Liviu Dudau
2014-04-07 22:44 ` Bjorn Helgaas
2014-04-08 10:20 ` Liviu Dudau
2014-04-08 16:28 ` Bjorn Helgaas
2014-04-09 12:07 ` Liviu Dudau
2014-04-09 14:02 ` Bjorn Helgaas
2014-04-09 14:08 ` Arnd Bergmann
2014-04-09 23:49 ` Benjamin Herrenschmidt
2014-04-10 1:27 ` Liviu Dudau
2014-04-10 3:48 ` Bjorn Helgaas
2014-04-10 8:00 ` Arnd Bergmann
2014-04-10 13:50 ` Bjorn Helgaas
2014-04-10 14:07 ` Arnd Bergmann
2014-04-10 14:53 ` Liviu Dudau
2014-04-10 20:46 ` Arnd Bergmann
2014-04-11 5:01 ` Benjamin Herrenschmidt
2014-04-11 8:36 ` Arnd Bergmann
2014-04-11 9:16 ` Benjamin Herrenschmidt
2014-04-11 9:22 ` Liviu Dudau
2014-04-11 13:51 ` Arnd Bergmann
2014-07-01 16:37 ` Liviu Dudau
2014-07-04 14:57 ` Liviu Dudau
2014-07-08 1:11 ` Bjorn Helgaas
2014-07-08 10:21 ` Liviu Dudau
2014-03-14 15:34 ` [PATCH v7 5/6] pci: Export find_pci_host_bridge() function Liviu Dudau
2014-04-04 23:39 ` Bjorn Helgaas
2014-04-07 14:20 ` Liviu Dudau
2014-04-07 14:38 ` One Thousand Gnomes
2014-03-14 15:34 ` [PATCH v7 6/6] pci: Add support for creating a generic host_bridge from device tree Liviu Dudau
2014-04-08 12:57 ` Hanjun Guo
2014-04-08 13:09 ` Liviu Dudau
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