1STRUCT I2C_ADAPTER_Q(9)     I2C and SMBus Subsystem    STRUCT I2C_ADAPTER_Q(9)
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NAME

6       struct_i2c_adapter_quirks - describe flaws of an i2c adapter
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SYNOPSIS

9       struct i2c_adapter_quirks {
10         u64 flags;
11         int max_num_msgs;
12         u16 max_write_len;
13         u16 max_read_len;
14         u16 max_comb_1st_msg_len;
15         u16 max_comb_2nd_msg_len;
16       };
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MEMBERS

19       flags
20           see I2C_AQ_* for possible flags and read below
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22       max_num_msgs
23           maximum number of messages per transfer
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25       max_write_len
26           maximum length of a write message
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28       max_read_len
29           maximum length of a read message
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31       max_comb_1st_msg_len
32           maximum length of the first msg in a combined message
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34       max_comb_2nd_msg_len
35           maximum length of the second msg in a combined message
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NOTE ABOUT COMBINED MESSAGES

38       Some I2C controllers can only send one message per transfer, plus
39       something called combined message or write-then-read. This is (usually)
40       a small write message followed by a read message and barely enough to
41       access register based devices like EEPROMs. There is a flag to support
42       this mode. It implies max_num_msg = 2 and does the length checks with
43       max_comb_*_len because combined message mode usually has its own
44       limitations. Because of HW implementations, some controllers can
45       actually do write-then-anything or other variants. To support that,
46       write-then-read has been broken out into smaller bits like write-first
47       and read-second which can be combined as needed.
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50Kernel Hackers Manual 3.10         June 2019           STRUCT I2C_ADAPTER_Q(9)
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