1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>struct i2c_adapter_quirks</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="Linux Device Drivers"><link rel="up" href="i2c.html" title="Chapter&#160;10.&#160;I2C and SMBus Subsystem"><link rel="prev" href="API-struct-i2c-bus-recovery-info.html" title="struct i2c_bus_recovery_info"><link rel="next" href="API-module-i2c-driver.html" title="module_i2c_driver"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span class="phrase">struct i2c_adapter_quirks</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-struct-i2c-bus-recovery-info.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;10.&#160;I<sup>2</sup>C and SMBus Subsystem</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-module-i2c-driver.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-struct-i2c-adapter-quirks"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>struct i2c_adapter_quirks &#8212; 
2     describe flaws of an i2c adapter
3 </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="programlisting">
4struct i2c_adapter_quirks {
5  u64 flags;
6  int max_num_msgs;
7  u16 max_write_len;
8  u16 max_read_len;
9  u16 max_comb_1st_msg_len;
10  u16 max_comb_2nd_msg_len;
11};  </pre></div><div class="refsect1"><a name="idp1115300660"></a><h2>Members</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term">flags</span></dt><dd><p>
12   see I2C_AQ_* for possible flags and read below
13      </p></dd><dt><span class="term">max_num_msgs</span></dt><dd><p>
14   maximum number of messages per transfer
15      </p></dd><dt><span class="term">max_write_len</span></dt><dd><p>
16   maximum length of a write message
17      </p></dd><dt><span class="term">max_read_len</span></dt><dd><p>
18   maximum length of a read message
19      </p></dd><dt><span class="term">max_comb_1st_msg_len</span></dt><dd><p>
20   maximum length of the first msg in a combined message
21      </p></dd><dt><span class="term">max_comb_2nd_msg_len</span></dt><dd><p>
22   maximum length of the second msg in a combined message
23      </p></dd></dl></div></div><div class="refsect1"><a name="idp1115305612"></a><h2>Note about combined messages</h2><p>
24   Some I2C controllers can only send one message
25   per transfer, plus something called combined message or write-then-read.
26   This is (usually) a small write message followed by a read message and
27   barely enough to access register based devices like EEPROMs. There is a flag
28   to support this mode. It implies max_num_msg = 2 and does the length checks
29   with max_comb_*_len because combined message mode usually has its own
30   limitations. Because of HW implementations, some controllers can actually do
31   write-then-anything or other variants. To support that, write-then-read has
32   been broken out into smaller bits like write-first and read-second which can
33   be combined as needed.
34</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-struct-i2c-bus-recovery-info.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="i2c.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="API-module-i2c-driver.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">struct i2c_bus_recovery_info</span>&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;<span class="phrase">module_i2c_driver</span></td></tr></table></div></body></html>
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