STRUCT I2C_ADAPTER_Q(9)              I2C and SMBus Subsystem              STRUCT I2C_ADAPTER_Q(9)



NAME
       struct_i2c_adapter_quirks - describe flaws of an i2c adapter

SYNOPSIS
       struct i2c_adapter_quirks {
         u64 flags;
         int max_num_msgs;
         u16 max_write_len;
         u16 max_read_len;
         u16 max_comb_1st_msg_len;
         u16 max_comb_2nd_msg_len;
       };

MEMBERS
       flags
           see I2C_AQ_* for possible flags and read below

       max_num_msgs
           maximum number of messages per transfer

       max_write_len
           maximum length of a write message

       max_read_len
           maximum length of a read message

       max_comb_1st_msg_len
           maximum length of the first msg in a combined message

       max_comb_2nd_msg_len
           maximum length of the second msg in a combined message

DESCRIPTION
       Note about combined messages: Some I2C controllers can only send one message per transfer,
       plus something called combined message or write-then-read. This is (usually) a small write
       message followed by a read message and barely enough to access register based devices like
       EEPROMs. There is a flag to support this mode. It implies max_num_msg = 2 and does the
       length checks with max_comb_*_len because combined message mode usually has its own
       limitations. Because of HW implementations, some controllers can actually do
       write-then-anything or other variants. To support that, write-then-read has been broken
       out into smaller bits like write-first and read-second which can be combined as needed.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                   STRUCT I2C_ADAPTER_Q(9)