From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Jon Masters <jcm@jonmasters.org>
Cc: mark.rutland@arm.com, Catalin Marinas <catalin.marinas@arm.com>,
linux-pci@vger.kernel.org, lkml <linux-kernel@vger.kernel.org>,
Jeremy Linton <jeremy.linton@arm.com>,
Bjorn Helgaas <helgaas@kernel.org>,
sudeep.holla@arm.com, Bjorn Helgaas <bhelgaas@google.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: PCI: Enable SMC conduit
Date: Thu, 25 Feb 2021 09:30:00 +0000 [thread overview]
Message-ID: <20210225093000.GA22843@e121166-lin.cambridge.arm.com> (raw)
In-Reply-To: <CACCGGCc3zULqHgUh3Q9wA5WtPBnQ4eq_v2+1qA8bOBCQZJ5YoQ@mail.gmail.com>
On Thu, Feb 18, 2021 at 12:43:30PM -0500, Jon Masters wrote:
> Hi Bjorn, all,
>
> On Thu, Jan 28, 2021 at 6:31 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Tue, Jan 26, 2021 at 10:46:04AM -0600, Jeremy Linton wrote:
>
>
>
> > Does that mean its open season for ECAM quirks, and we can expect
> > them to start being merged now?
>
> "Open season" makes me cringe because it suggests we have a license to
> use quirks indiscriminately forever, and I hope that's not the case.
>
> Lorenzo is closer to this issue than I am and has much better insight
> into the mess this could turn into. From my point of view, it's
> shocking how much of a hassle this is compared to x86. There just
> aren't ECAM quirks, in-kernel clock management, or any of that crap.
> I don't know how they do it on x86 and I don't have to care. Whatever
> they need to do, they apparently do in AML. Eventually ARM64 has to
> get there as well if vendors want distro support.
>
> I don't want to be in the position of enforcing a draconian "no more
> quirks ever" policy. The intent -- to encourage/force vendors to
> develop spec-compliant machines -- is good, but it seems like the
> reward of having compliant machines "just work" vs the penalty of
> having to write quirks and shepherd them upstream and into distros
> will probably be more effective and not much slower.
>
>
> The problem is that the third party IP vendors (still) make too much junk. For
> years, there wasn't a compliance program (e.g. SystemReady with some of the
> meat behind PCI-SIG compliance) and even when there was the third party IP
> vendors building "root ports" (not even RCs) would make some junk with a hacked
> up Linux kernel booting on a model and demo that as "PCI". There wasn't the
> kind of adult supervision that was required. It is (slowly) happening now, but
> it's years and years late. It's just embarrassing to see the lack of ECAM that
> works. In many cases, it's because the IP being used was baked years ago or
> made for some "non server" (as if there is such a thing) use case, etc. But in
> others, there was a chance to do it right, and it still happens. Some of us
> have lost what hair we had over the years getting third party IP vendors to
> wake up and start caring about this.
>
> So there's no excuse. None at all. However, this is where we are. And it /is/
> improving. But it's still too slow, and we have platforms still coming to
> market that need to boot and run. Based on this, and the need to have something
> more flexible than just solving for ECAM deficiencies (which are really just a
> symptom), I can see the allure of an SMC. I don't like it, but if that's where
> folks want to go, and if we can find a way to constrain the enthusiasm for it,
> then perhaps it is a path forward. But if we are to go down that path it needs
> to come with a giant warning from the kernel that a system was booted at is
> relying on that. Something that will cause an OS certification program to fail
> without a waiver, or will cause customers to phone up for support wondering why
> the hw is broken. It *must* not be a silent thing. It needs to be "this
> hardware is broken and non-standard, get the next version fixed".
It is a stance I agree with in many respects, it should be shared (it
was in HTML format - the lists unfortunately dropped the message) so I
am replying to it to make it public.
Thanks,
Lorenzo
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-02-25 9:32 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-05 4:57 [PATCH] arm64: PCI: Enable SMC conduit Jeremy Linton
2021-01-07 15:28 ` Rob Herring
2021-01-07 16:23 ` Jeremy Linton
2021-01-07 17:36 ` Rob Herring
2021-01-07 19:45 ` Jeremy Linton
2021-01-07 20:35 ` Rob Herring
2021-01-07 18:14 ` Will Deacon
2021-01-07 19:18 ` Jeremy Linton
2021-01-07 21:05 ` Jon Masters
2021-01-07 21:49 ` Rob Herring
2021-01-08 10:32 ` Lorenzo Pieralisi
2021-01-22 19:48 ` Will Deacon
2021-01-26 16:46 ` Jeremy Linton
2021-01-26 22:54 ` Will Deacon
2021-01-28 18:50 ` Jeremy Linton
2021-01-28 23:31 ` Bjorn Helgaas
[not found] ` <CACCGGCc3zULqHgUh3Q9wA5WtPBnQ4eq_v2+1qA8bOBCQZJ5YoQ@mail.gmail.com>
2021-02-25 9:30 ` Lorenzo Pieralisi [this message]
2021-02-25 22:31 ` Jeremy Linton
2021-01-26 17:08 ` Vikram Sethi
2021-01-26 22:53 ` Will Deacon
2021-03-25 13:12 ` Lorenzo Pieralisi
2021-03-25 20:45 ` Marcin Wojtas
2021-03-25 21:12 ` Jon Masters
2021-03-26 9:27 ` Marcin Wojtas
2021-06-16 17:36 ` Jason Gunthorpe
[not found] ` <CA+kK7ZijdNERQSauEvAffR7JLbfZ512na2-9cJrU0vFbNnDGwQ@mail.gmail.com>
2021-06-18 14:05 ` Jason Gunthorpe
2021-06-19 16:34 ` Jon Masters
2021-06-19 16:38 ` Jon Masters
2021-06-20 0:26 ` Jason Gunthorpe
2021-06-18 15:10 ` Jeremy Linton
2021-01-12 16:16 ` Vidya Sagar
2021-01-12 16:57 ` Jeremy Linton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210225093000.GA22843@e121166-lin.cambridge.arm.com \
--to=lorenzo.pieralisi@arm.com \
--cc=bhelgaas@google.com \
--cc=catalin.marinas@arm.com \
--cc=helgaas@kernel.org \
--cc=jcm@jonmasters.org \
--cc=jeremy.linton@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=sudeep.holla@arm.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).