From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Bjorn Helgaas <helgaas@kernel.org>, Arnd Bergmann <arnd@arndb.de>
Cc: "Saheed O. Bolarinwa" <refactormyself@gmail.com>,
bjorn@helgaas.com, Shuah Khan <skhan@linuxfoundation.org>,
linux-pci <linux-pci@vger.kernel.org>,
linux-kernel-mentees@lists.linuxfoundation.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Richard Henderson <rth@twiddle.net>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Greg Ungerer <gerg@linux-m68k.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Russell King <linux@armlinux.org.uk>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Michael Ellerman <mpe@ellerman.id.au>,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
"David S. Miller" <davem@davemloft.net>,
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Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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Jakub Kicinski <kuba@kernel.org>, Keith Busch <kbusch@kernel.org>,
Jens Axboe <axboe@fb.com>, Christoph Hellwig <hch@lst.de>,
Sagi Grimberg <sagi@grimberg.me>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Rob Herring <robh@kernel.org>,
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Jingoo Han <jingoohan1@gmail.com>,
Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
Toan Le <toan@os.amperecomputing.com>,
Ray Jui <rjui@broadcom.com>,
Scott Branden <sbranden@broadcom.com>,
Ley Foon Tan <ley.foon.tan@intel.com>,
Marek Vasut <marek.vasut+renesas@gmail.com>
Subject: Re: [RFC PATCH 00/35] Move all PCIBIOS* definitions into arch/x86
Date: Wed, 15 Jul 2020 12:12:29 +1000 [thread overview]
Message-ID: <fb40545a8de8df8914df40d7d6167752c5244ce6.camel@kernel.crashing.org> (raw)
In-Reply-To: <20200714184550.GA397277@bjorn-Precision-5520>
On Tue, 2020-07-14 at 13:45 -0500, Bjorn Helgaas wrote:
>
> > fail for valid arguments on a valid pci_device* ?
>
> I really like this idea.
>
> pci_write_config_*() has one return value, and only 100ish of 2500
> callers check for errors. It's sometimes possible for config
> accessors to detect PCI errors and return failure, e.g., device was
> removed or didn't respond, but most of them don't, and detecting
> these
> errors is not really that valuable.
>
> pci_read_config_*() is much more interesting because it returns two
> things, the function return value and the value read from the PCI
> device, and it's complicated to check both.
.../...
I agree. It's a mess at the moment.
We have separate mechanism to convey PCI errors (among other things the
channel state) which should apply to config space when detection is
possible.
I think returning all 1's is the right thing to do here and avoids odd
duplicate error detection logic which I bet you is never properly
tested.
> > For b), it might be nice to also change other aspects of the
> > interface, e.g. passing a pci_host_bridge pointer plus bus number
> > instead of a pci_bus pointer, or having the callback in the
> > pci_host_bridge structure.
>
> I like this idea a lot, too. I think the fact that
> pci_bus_read_config_word() requires a pci_bus * complicates things in
> a few places.
>
> I think it's completely separate, as you say, and we should defer it
> for now because even part a) is a lot of work. I added it to my list
> of possible future projects.
Agreed on both points.
Cheers,
Ben.
prev parent reply other threads:[~2020-07-15 2:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAK8P3a3NWSZw6678k1O2eJ6-c5GuW7484PRvEzU9MEPPrCD-yw@mail.gmail.com>
2020-07-14 18:45 ` [RFC PATCH 00/35] Move all PCIBIOS* definitions into arch/x86 Bjorn Helgaas
2020-07-14 21:02 ` Kjetil Oftedal
2020-07-15 2:14 ` Benjamin Herrenschmidt
2020-07-14 22:01 ` Arnd Bergmann
2020-07-14 23:46 ` Bjorn Helgaas
2020-07-15 2:19 ` Benjamin Herrenschmidt
2020-07-15 6:47 ` Arnd Bergmann
2020-07-15 22:26 ` Benjamin Herrenschmidt
2020-07-15 4:18 ` Oliver O'Halloran
2020-07-15 14:38 ` David Laight
2020-07-15 22:12 ` Bjorn Helgaas
2020-07-15 22:49 ` Benjamin Herrenschmidt
2020-07-16 8:07 ` David Laight
2020-07-14 23:14 ` Rob Herring
2020-07-15 2:12 ` Benjamin Herrenschmidt [this message]
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