From: Wolfram Sang <wsa@kernel.org>
To: Marek Behun <marek.behun@nic.cz>
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: Fri, 8 Jan 2021 09:40:51 +0100 [thread overview]
Message-ID: <20210108084051.GA1223@kunai> (raw)
In-Reply-To: <20210107224211.4f01c055@nic.cz>
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> 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...
Well, sure, you can never know what crazy HW is out there :) But that
shouldn't prevent us from doing legit I2C transfers. The likeliness of
such HW is low enough; They must process the whole transfer in one go
(rare) AND have the limitiation with the buffer pointers (at least I
don't know one) AND have no possibility of a fallback to a simpler mode
where they can handle the transfer per message. If such a controller
exists, it would need a new quirk flag, I'd say, and reject the
transfer. But that shouldn't stop you from fixing your issue.
Thanks for thinking thoroughly about drawbacks! Much appreciated.
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prev parent reply other threads:[~2021-01-08 8:41 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
2021-01-08 8:40 ` Wolfram Sang [this message]
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