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From: Lorenzo Pieralisi <>
To: Jon Masters <>
Cc: Bjorn Helgaas <>,
	Jeremy Linton <>,
	Will Deacon <>,,,, lkml <>,
	Catalin Marinas <>,
	Bjorn Helgaas <>,
Subject: Re: [PATCH] arm64: PCI: Enable SMC conduit
Date: Thu, 25 Feb 2021 09:30:00 +0000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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 <> 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.


  parent reply	other threads:[~2021-02-25  9:31 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]             ` <>
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]                 ` <>
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

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