netdev - RE: [PATCH net-next v3 2/8] i2c: designware: Add driver support for Wangxun 10Gb NIC

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Date:   Thu, 20 Apr 2023 18:29:11 +0800
From:   Jiawen Wu <jiawenwu@...stnetic.com>
To:     "'Andrew Lunn'" <andrew@...n.ch>
Cc:     <netdev@...r.kernel.org>, <linux@...linux.org.uk>,
        <linux-i2c@...r.kernel.org>, <linux-gpio@...r.kernel.org>,
        <olteanv@...il.com>, <mengyuanlou@...-swift.com>,
        "'Jarkko Nikula'" <jarkko.nikula@...ux.intel.com>
Subject: RE: [PATCH net-next v3 2/8] i2c: designware: Add driver support for Wangxun 10Gb NIC

On Thursday, April 20, 2023 4:58 AM, Andrew Lunn wrote:
> On Wed, Apr 19, 2023 at 04:27:33PM +0800, Jiawen Wu wrote:
> > Wangxun 10Gb ethernet chip is connected to Designware I2C, to communicate
> > with SFP.
> >
> > Add platform data to pass IOMEM base address, board flag and other
> > parameters, since resource address was mapped on ethernet driver.
> >
> > The exists IP limitations are dealt as workarounds:
> > - IP does not support interrupt mode, it works on polling mode.
> > - I2C cannot read continuously, only one byte can at a time.
> 
> Are you really sure about that?
> 
> It is a major limitation for SFP devices. It means you cannot access
> the diagnostics, since you need to perform an atomic 2 byte read.
> 
> Or maybe i'm understanding you wrong.
> 
>    Andrew
> 

Maybe I'm a little confused about this. Every time I read a byte info, I have to
write a 'read command'. It can normally get the information for SFP devices.
But I'm not sure if this is regular I2C behavior.