Re: ioremap_uc() followed by set_memory_wc() - burrying MTRR

From: Doug Ledford <dledford@redhat.com>
To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: "Luis R. Rodriguez" <mcgrof@suse.com>,
	Andy Lutomirski <luto@amacapital.net>,
	mike.marciniszyn@intel.com, infinipath@intel.com,
	linux-rdma@vger.kernel.org, awalls@md.metrocast.net,
	Toshi Kani <toshi.kani@hp.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Ingo Molnar <mingo@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Hal Rosenstock <hal.rosenstock@gmail.com>,
	Sean Hefty <sean.hefty@intel.com>,
	Suresh Siddha <sbsiddha@gmail.com>,
	Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>,
	Roland Dreier <roland@purestorage.com>,
	Juergen Gross <jgross@suse.com>,
	Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
	Borislav Petkov <bp@suse.de>, Mel Gorman <mgorman@suse.de>,
	Vlastimil Babka <vbabka@suse.cz>,
	Davidlohr Bueso <dbueso@suse.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ville Syrj?l? <syrjala@sci.fi>,
	Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
	linux-media@vger.kernel.org, X86 ML <x86@kernel.org>,
	mcgrof@do-not-panic.com
Subject: Re: ioremap_uc() followed by set_memory_wc() - burrying MTRR
Date: Wed, 22 Apr 2015 16:58:59 -0400	[thread overview]
Message-ID: <1429736339.121496.25.camel@redhat.com> (raw)
In-Reply-To: <20150422204637.GA29491@obsidianresearch.com>

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On Wed, 2015-04-22 at 14:46 -0600, Jason Gunthorpe wrote:
> On Wed, Apr 22, 2015 at 02:53:11PM -0400, Doug Ledford wrote:
> 
> > To be precise, the split is that ipath powers the old HTX bus cards that
> > only work in AMD systems, qib is all PCI-e cards.  I still have a few
> > HTX cards, but I no longer have any systems with HTX slots, so we
> > haven't even used this driver in testing for 3 or 4 years now.  And
> > these are all old SDR cards, where the performance numbers were 800MB/s
> > with WC enabled, 50MB/s without it.
> 
> Wow, I doubt any HTX systems are still in any kind of use.
> 
> It would be a nice clean up to drop the PPC support out of this driver
> too. PPC never had HTX.

commit f6d60848baf9f4015c76c665791875ed623cd5b7
Author: Ralph Campbell <ralph.campbell@qlogic.com>
Date:   Thu May 6 17:03:19 2010 -0700

    IB/ipath: Remove support for QLogic PCIe QLE devices

    The ib_qib driver is taking over support for QLogic PCIe QLE
devices,
    so remove support for them from ib_ipath.  The ib_ipath driver now
    supports only the obsolete QLogic Hyper-Transport IB host channel
    adapter (model QHT7140).

    Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
    Signed-off-by: Roland Dreier <rolandd@cisco.com>

There you go.  It's been HTX only since 2010, and those cards were
already old then.  I think we should seriously consider deprecating and
then removing the driver.

-- 
Doug Ledford <dledford@redhat.com>
              GPG KeyID: 0E572FDD

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