From: Marek Behun <marek.behun@nic.cz>
To: Wolfram Sang <wsa@kernel.org>
Cc: "Russell King - ARM Linux admin" <linux@armlinux.org.uk>,
"Andrew Lunn" <andrew@lunn.ch>,
netdev@vger.kernel.org, "Pali Rohár" <pali@kernel.org>,
linux-i2c@vger.kernel.org
Subject: Re: question about i2c_transfer() function (regarding mdio-i2c on RollBall SFPs)
Date: Thu, 7 Jan 2021 22:42:11 +0100 [thread overview]
Message-ID: <20210107224211.4f01c055@nic.cz> (raw)
In-Reply-To: <20210107210248.GA894@kunai>
On Thu, 7 Jan 2021 22:02:48 +0100
Wolfram Sang <wsa@kernel.org> wrote:
> > My question is whether this is allowed, whether the msgs array passed
> > to the i2c_transfer() function can have multiple msgs pointing to the
> > same buffer (the one into which the original page is first stored
> > with first i2c_msg and then restored from it in the last i2c_msg).
>
> Sending the messages is serialized, so the buffers won't interfere. At
> first glance, I think it would work this way. But it's late evening
> here, so I will have another look again tomorrow.
>
I thought as much, but maybe there is some driver which can offload
whole i2c_transfer to HW, and has to pass the addresses of the buffers
to the HW, and the HW can have problems if the buffers overlap
somewhere...
Marek
next prev parent reply other threads:[~2021-01-07 21:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-07 18:25 question about i2c_transfer() function (regarding mdio-i2c on RollBall SFPs) Marek Behun
2021-01-07 21:02 ` Wolfram Sang
2021-01-07 21:42 ` Marek Behun [this message]
2021-01-08 8:40 ` Wolfram Sang
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