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From: Logan Gunthorpe <logang@deltatee.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	linux-ntb@googlegroups.com, linux-crypto@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jyri Sarha <jsarha@ti.com>, Stephen Bates <sbates@raithlin.com>,
	Christoph Hellwig <hch@lst.de>,
	Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH v2 1/3] io-64-nonatomic: add io{read|write}64[be] macros
Date: Wed, 28 Jun 2017 10:02:57 -0600	[thread overview]
Message-ID: <e32bd057-2069-63c9-b75d-3a97a736d898@deltatee.com> (raw)
In-Reply-To: <CAK8P3a2tL5wdCRscpyb6fW+LQVM05urud=YQRS-3+=4w53rmvg@mail.gmail.com>



On 28/06/17 04:11 AM, Arnd Bergmann wrote:
> This is wrong since ioread* is not the same read* on x86 and other
> architectures that have native PCI PIO accessors, or that require
> additional barriers for those.
> 
> You have to copy hi_lo_readq() here, and call ioread32 twice instead
> of calling readl() twice. Same for iowrite64.
> 
>> +#ifndef ioread64be
>> +#define ioread64be(p) be64_to_cpu(ioread64(p))
>> +#endif
> 
> This has another problem: ioread64() is defined to access little-endian
> registers, just like readq(). This means that instead of be64_to_cpu()
> you need swab64() and always perform the byte swap, otherwise this
> would be broken on big-endian architectures.

Ah, ok, understood. I'll see if I can fix both these issues.

Thanks,

Logan

  reply	other threads:[~2017-06-28 16:03 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-27 23:02 [PATCH v2 0/3] make io{read|write}64 more globally usable Logan Gunthorpe
2017-06-27 23:02 ` [PATCH v2 1/3] io-64-nonatomic: add io{read|write}64[be] macros Logan Gunthorpe
2017-06-28 10:11   ` Arnd Bergmann
2017-06-28 16:02     ` Logan Gunthorpe [this message]
2017-06-27 23:02 ` [PATCH v2 2/3] ntb: ntb_hw_intel: use io-64-nonatomic instead of in-driver hacks Logan Gunthorpe
2017-06-27 23:02 ` [PATCH v2 3/3] crypto: caam: cleanup CONFIG_64BIT ifdefs when using io{read|write}64 Logan Gunthorpe
2017-06-28 10:20   ` Arnd Bergmann
2017-06-28 16:51     ` Logan Gunthorpe
2017-06-29  7:52       ` Horia Geantă

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