Re: [virtio-dev] Re: [PATCH v2] virtio-i2c: add the device specification

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Oct 26, 2020 at 09:22:07AM +0800, Jie Deng wrote:
> On 2020/10/24 0:00, Michael S. Tsirkin wrote:
> 
> > On Fri, Oct 23, 2020 at 02:51:25PM +0800, Jie Deng wrote:
> > > +
> > > +The driver queues requests to the virtqueues, and they are used by the
> > > +device. The request is the representation of one segment of an I2C
> > > +transaction. Each request is of form:
> > > +
> > > +\begin{lstlisting}
> > > +struct virtio_i2c_req {
> > > +        le16 addr;
> > > +        le16 flags;
> > > +        le16 len;
> > > +        u8 buf[];
> > > +        u8 status;
> > > +};
> > > +\end{lstlisting}
> > > +
> > > +The \field{addr} is the address of the I2C slave device.
> > > +
> > > +The first bit of \field{flags} indicates whether it is a read or write request.
> > > +It means a read request if the first bit of \field{flags} is set, otherwise
> > > +it is a write request. The rest bits of \field{flags} are reserved.
> > > 
> > 
> > So how does one creates a multi-segment transaction then?
> > 
> The I2C doesn't support segments numbering and sorting.
> So if one creates a multi-segment transaction, then he/she should keep the
> segments in order.
> 
> Thanks.

Fine, but I see no flags to signal start/end of such a transaction.

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