It'd always be a write followed by a read. Usually the write provides the number of a register to be read.
The opposite order does not make much sense. Paolo Il gio 5 nov 2020, 07:35 Jie Deng <[email protected]> ha scritto: > > On 2020/10/31 21:58, Paolo Bonzini wrote: > > On 27/10/20 12:20, Michael S. Tsirkin wrote: > > 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. > > > > In theory there's no difference between one multi-segment transaction > and many single-segment transactions _in a single-master scenario_. > > However, it is a plausible configuration to have multiple guests sharing > an I2C host device as if they were multiple master. > > For this reason, I would prefer to have at least support for > transactions with 1 write and 1 read segment to the same address (see my > other message). > > Paolo > > Then how to distinguish the order of the two segments if they are in one > request ? > We don't know this is a write followed by a read or a read followed by a > write in this case. > > However, if the request is the representation of only one segment of an > I2C transaction, > we can simply judge by the order of the requests in the virtqueue. > > Thanks > >
