Re: [RFC] asm-generic/pci_iomap.h: make custom PCI BAR requirements explicit

From	Martin Schwidefsky <schwidefsky@de.ibm.com>
Newsgroups	linux.kernel
Subject	Re: [RFC] asm-generic/pci_iomap.h: make custom PCI BAR requirements explicit
Date	2015-10-06 13:20 +0200
Message-ID	<qgyrL-4xj-9@gated-at.bofh.it> (permalink)
References	<q2C2d-2c4-3@gated-at.bofh.it> <q6rrA-5QO-17@gated-at.bofh.it> <qfip4-1IO-9@gated-at.bofh.it> <qfWPv-Ok-5@gated-at.bofh.it> <qghqW-5ar-27@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Mon, 5 Oct 2015 19:09:14 +0200
"Luis R. Rodriguez" <mcgrof@suse.com> wrote:

> On Sun, Oct 04, 2015 at 09:02:04PM +0200, Arnd Bergmann wrote:
> > On Saturday 03 October 2015 01:53:46 Luis R. Rodriguez wrote:
> > > > 
> > > > Hmm, my gut feeling tells me that your approach won't solve the problem
> > > > in general. s390 PCI is just weird in many ways and it will occasionally
> > > > suffer from problems like this (as do other aspects of the s390 architecture
> > > > that are unlike the rest of the world).
> > > > 
> > > > Maybe Martin and Heiko can comment on this, they may have a preference
> > > > from the s390 point of view.
> > > 
> > > Hrm, so S390 is quirky is really odd ways that no other architecture is or
> > > is at least for now not expected to be ?
> > 
> > Absolutely correct. It is the only architecture I'm aware of that tries to
> > support PCI that does not use pointer dereferences for MMIO.
> 
> So its not worth it to have a formal semantic via Kconfig for this and are
> happy with the status quo of having to find out through a bot compile test
> any changes in this domain fails?

For my part I still do not see the value in ARCH_PCI_NON_DISJUNCTIVE.
The existing GENERIC_PCI_IOMAP already allows an architecture to select
the generic implementation (or not to select it). To add another Kconfig
symbol and make GENERIC_PCI_IOMAP depend on it doesn't help.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

Re: [RFC] asm-generic/pci_iomap.h: make custom PCI BAR requirements  explicit "Luis R. Rodriguez" <mcgrof@suse.com> - 2015-10-03 02:00 +0200
  Re: [RFC] asm-generic/pci_iomap.h: make custom PCI BAR requirements explicit Arnd Bergmann <arnd@arndb.de> - 2015-10-04 21:10 +0200
    Re: [RFC] asm-generic/pci_iomap.h: make custom PCI BAR requirements  explicit "Luis R. Rodriguez" <mcgrof@suse.com> - 2015-10-05 19:10 +0200
      Re: [RFC] asm-generic/pci_iomap.h: make custom PCI BAR requirements  explicit Martin Schwidefsky <schwidefsky@de.ibm.com> - 2015-10-06 13:20 +0200

csiph-web