From: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: linux-arch@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
Stephen Bates <sbates@raithlin.com>,
linux-crypto@vger.kernel.org, linux-alpha@vger.kernel.org,
linux-ntb@googlegroups.com, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 3/7] asm-generic/io.h: make ioread64 and iowrite64 universally available
Date: Thu, 22 Jun 2017 21:36:55 +0100 [thread overview]
Message-ID: <20170622213655.07dffac2@alans-desktop> (raw)
In-Reply-To: <e856de0b-e9a3-8228-7a73-4daa38cb4479@deltatee.com>
On Thu, 22 Jun 2017 14:24:58 -0600
Logan Gunthorpe <logang@deltatee.com> wrote:
> On 6/22/2017 2:14 PM, Alan Cox wrote:
> > If a platform doesn't support 64bit I/O operations from the CPU then you
> > either need to use some kind of platform/architecture specific interface
> > if present or accept you don't have one.
>
> Yes, I understand that.
>
> The thing is that every user that's currently using it right now is
> patching in their own version that splits it on non-64bit systems.
>
> > It's not safe to split it. Possibly for some use cases you could add an
> > ioread64_maysplit()
>
> I'm open to doing something like that.
I think that makes sense for the platforms with that problem. I'm not
sure there are many that can't do it for mmio at least. 486SX can't do it
and I guess some ARM32 but I think almost everyone else can including
most 32bit x86.
What's more of a problem is a lot of platforms can do 64bit MMIO via
ioread/write64 but not 64bit port I/O, and it's not clear how you
represent that via an ioread/write API that abstracts it away.
Alan
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WARNING: multiple messages have this Message-ID (diff)
From: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
linux-ntb@googlegroups.com, linux-alpha@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-crypto@vger.kernel.org,
dri-devel@lists.freedesktop.org, Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Stephen Bates <sbates@raithlin.com>
Subject: Re: [PATCH 3/7] asm-generic/io.h: make ioread64 and iowrite64 universally available
Date: Thu, 22 Jun 2017 21:36:55 +0100 [thread overview]
Message-ID: <20170622213655.07dffac2@alans-desktop> (raw)
Message-ID: <20170622203655.B_JlhMS_8RjWUwIybgydtzCbkSQgZnacGJVN96s5usY@z> (raw)
In-Reply-To: <e856de0b-e9a3-8228-7a73-4daa38cb4479@deltatee.com>
On Thu, 22 Jun 2017 14:24:58 -0600
Logan Gunthorpe <logang@deltatee.com> wrote:
> On 6/22/2017 2:14 PM, Alan Cox wrote:
> > If a platform doesn't support 64bit I/O operations from the CPU then you
> > either need to use some kind of platform/architecture specific interface
> > if present or accept you don't have one.
>
> Yes, I understand that.
>
> The thing is that every user that's currently using it right now is
> patching in their own version that splits it on non-64bit systems.
>
> > It's not safe to split it. Possibly for some use cases you could add an
> > ioread64_maysplit()
>
> I'm open to doing something like that.
I think that makes sense for the platforms with that problem. I'm not
sure there are many that can't do it for mmio at least. 486SX can't do it
and I guess some ARM32 but I think almost everyone else can including
most 32bit x86.
What's more of a problem is a lot of platforms can do 64bit MMIO via
ioread/write64 but not 64bit port I/O, and it's not clear how you
represent that via an ioread/write API that abstracts it away.
Alan
next prev parent reply other threads:[~2017-06-22 20:36 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-22 16:48 [PATCH 0/7] cleanup issues with io{read|write}64 Logan Gunthorpe
2017-06-22 16:48 ` [PATCH 1/7] drm/tilcdc: don't use volatile with iowrite64 Logan Gunthorpe
2017-06-26 8:54 ` Jyri Sarha
2017-06-26 8:54 ` Jyri Sarha
2017-06-26 8:54 ` Jyri Sarha
2017-06-26 8:54 ` Jyri Sarha
2017-06-22 16:48 ` [PATCH 2/7] iomap: implement ioread64 and iowrite64 Logan Gunthorpe
2017-06-26 20:43 ` Arnd Bergmann
2017-06-26 21:25 ` Logan Gunthorpe
2017-06-22 16:48 ` [PATCH 3/7] asm-generic/io.h: make ioread64 and iowrite64 universally available Logan Gunthorpe
2017-06-22 20:14 ` Alan Cox
2017-06-22 20:14 ` Alan Cox
2017-06-22 20:24 ` Logan Gunthorpe
2017-06-22 20:36 ` Alan Cox [this message]
2017-06-22 20:36 ` Alan Cox
2017-06-22 20:38 ` Logan Gunthorpe
2017-06-22 16:48 ` [PATCH 4/7] alpha: provide ioread64 and iowrite64 implementations Logan Gunthorpe
2017-06-22 17:29 ` Stephen Bates
2017-06-22 17:29 ` Stephen Bates
2017-06-22 17:30 ` Logan Gunthorpe
2017-06-22 20:08 ` Alan Cox
2017-06-22 20:09 ` Logan Gunthorpe
2017-06-22 21:03 ` Arnd Bergmann
2017-06-22 21:03 ` Arnd Bergmann
2017-06-22 21:10 ` Logan Gunthorpe
2017-06-22 21:20 ` Richard Henderson
2017-06-22 16:48 ` [PATCH 5/7] ntb: ntb_hw_intel: remove ioread64 and iowrite64 hacks Logan Gunthorpe
2017-06-22 17:17 ` Jiang, Dave
2017-06-22 17:17 ` Jiang, Dave
2017-06-22 17:17 ` Jiang, Dave
2017-06-22 16:48 ` [PATCH 6/7] drm/tilcdc: clean up ifdef hacks around iowrite64 Logan Gunthorpe
2017-06-26 8:55 ` Jyri Sarha
2017-06-26 8:55 ` Jyri Sarha
2017-06-26 8:55 ` Jyri Sarha
2017-06-26 8:55 ` Jyri Sarha
2017-06-26 16:26 ` Logan Gunthorpe
2017-06-27 20:40 ` Arnd Bergmann
2017-06-22 16:48 ` [PATCH 7/7] crypto: caam: cleanup CONFIG_64BIT ifdefs when using io{read|write}64 Logan Gunthorpe
2017-06-22 16:48 ` Logan Gunthorpe
2017-06-23 6:51 ` Horia Geantă
2017-06-23 6:51 ` Horia Geantă
2017-06-23 6:51 ` Horia Geantă
2017-06-23 17:59 ` Logan Gunthorpe
2017-06-23 17:59 ` Logan Gunthorpe
2017-06-23 17:59 ` Logan Gunthorpe
2017-06-24 11:57 ` [PATCH v2 " Horia Geantă
2017-06-24 11:57 ` Horia Geantă
2017-06-24 15:13 ` [PATCH] alpha: provide ioread64 and iowrite64 implementations Richard Henderson
2017-06-24 15:19 ` Logan Gunthorpe
2017-06-24 15:25 ` Richard Henderson
2017-06-24 15:32 ` Logan Gunthorpe
2017-06-24 16:14 ` Richard Henderson
2017-06-24 17:17 ` Logan Gunthorpe
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