<?xml version="1.0" encoding="ANSI_X3.4-1968" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>usb_ep_fifo_status</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="USB Gadget API for Linux" /><link rel="up" href="ch03s03.html" title="Core Objects and Methods" /><link rel="prev" href="re26.html" title="usb_ep_set_wedge" /><link rel="next" href="re28.html" title="usb_ep_fifo_flush" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>usb_ep_fifo_status</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re26.html">Prev</a> </td><th width="60%" align="center">Core Objects and Methods</th><td width="20%" align="right"> <a accesskey="n" href="re28.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="usb_ep_fifo_status"><a id="API-usb-ep-fifo-status"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>usb_ep_fifo_status — returns number of bytes in fifo, or error </p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">usb_ep_fifo_status </b>(</code></td><td>struct usb_ep * <var class="pdparam">ep</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id2994126"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>ep</code></em></span></dt><dd><p> the endpoint whose fifo status is being checked. </p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id2994152"></a><h2>Description</h2><p> FIFO endpoints may have <span class="quote">“<span class="quote">unclaimed data</span>”</span> in them in certain cases, such as after aborted transfers. Hosts may not have collected all the IN data written by the gadget driver (and reported by a request completion). The gadget driver may not have collected all the data written OUT to it by the host. Drivers that need precise handling for fault reporting or recovery may need to use this call. </p><p> This returns the number of such bytes in the fifo, or a negative errno if the endpoint doesn't use a FIFO or doesn't support such precise handling. </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re26.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch03s03.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re28.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>usb_ep_set_wedge</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span>usb_ep_fifo_flush</span></td></tr></table></div></body></html>