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

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.

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