From: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Alexandre Courbot
<gnurou-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
Thierry Reding
<thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>,
Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>,
Laxman Dewangan
<ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
Ben Dooks <ben.dooks-4yDnlxn2s6sWdaTGBSpHTA@public.gmane.org>,
Bob Mottram <bob.mottram-4yDnlxn2s6sWdaTGBSpHTA@public.gmane.org>,
"linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Linux Kernel Mailing List
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH 1/2] i2c: tegra: Maintain CPU endianness
Date: Thu, 22 Jan 2015 18:22:57 +0300 [thread overview]
Message-ID: <54C115D1.10206@gmail.com> (raw)
In-Reply-To: <CAAVeFuJHST9VOWXe_cZNvLmfGdamuU4HSgdZC6EoQvrsGFt+Fg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
22.01.2015 10:55, Alexandre Courbot пишет:
> On Thu, Jan 22, 2015 at 4:40 PM, Thierry Reding
> <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>
>> Should this not technically be le32_to_cpu() since the data originates
>> from the I2C controller?
No, i2c_readl returns value in CPU endianness, so it's correct. But for
i2c_writel should be used le32_to_cpu(), since it takes value in CPU endianness.
It's my overlook, V2 is coming.
>>
>> Why does this have to be initialized to 0 now?
>
> I suspect this is because we are going to memcpy less than 4 bytes
> into it, but I cannot figure out how that memcpy if guaranteed to
> produce the expected result for both endiannesses.
>
That's correct. Memcpy is working with bytes, so it doesn't care about
endianness and produces expected result, since I2C message is char array.
--
Dmitry
next prev parent reply other threads:[~2015-01-22 15:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-20 12:22 [PATCH 1/2] i2c: tegra: Maintain CPU endianness Dmitry Osipenko
[not found] ` <1421756555-20266-1-git-send-email-digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-01-22 7:40 ` Thierry Reding
2015-01-22 7:55 ` Alexandre Courbot
[not found] ` <CAAVeFuJHST9VOWXe_cZNvLmfGdamuU4HSgdZC6EoQvrsGFt+Fg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-22 15:22 ` Dmitry Osipenko [this message]
[not found] ` <54C115D1.10206-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-01-22 16:06 ` Dmitry Osipenko
[not found] ` <54C12010.8040504-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-01-22 17:18 ` Dmitry Osipenko
[not found] ` <54C130EA.2050505-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-01-23 9:45 ` Thierry Reding
2015-01-23 13:27 ` Dmitry Osipenko
[not found] ` <54C24C2B.1070907-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-01-23 14:52 ` Dmitry Osipenko
[not found] ` <54C2601A.7000005-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-01-26 16:03 ` Wolfram Sang
2015-01-26 16:11 ` Dmitry Osipenko
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