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+<title>Generic Error Codes</title>
+<table frame="none" pgwide="1" id="gen-errors">
+ <title>Generic error codes</title>
+ <tgroup cols="2">
+ &cs-str;
+ <tbody valign="top">
+ <!-- Keep it ordered alphabetically -->
+ <row>
+ <entry>EAGAIN (aka EWOULDBLOCK)</entry>
+ <entry>The ioctl can't be handled because the device is in state where
+ it can't perform it. This could happen for example in case where
+ device is sleeping and ioctl is performed to query statistics.
+ It is also returned when the ioctl would need to wait
+ for an event, but the device was opened in non-blocking mode.
+ </entry>
+ </row>
+ <row>
+ <entry>EBADF</entry>
+ <entry>The file descriptor is not a valid.</entry>
+ </row>
+ <row>
+ <entry>EBUSY</entry>
+ <entry>The ioctl can't be handled because the device is busy. This is
+ typically return while device is streaming, and an ioctl tried to
+ change something that would affect the stream, or would require the
+ usage of a hardware resource that was already allocated. The ioctl
+ must not be retried without performing another action to fix the
+ problem first (typically: stop the stream before retrying).</entry>
+ </row>
+ <row>
+ <entry>EFAULT</entry>
+ <entry>There was a failure while copying data from/to userspace,
+ probably caused by an invalid pointer reference.</entry>
+ </row>
+ <row>
+ <entry>EINVAL</entry>
+ <entry>One or more of the ioctl parameters are invalid or out of the
+ allowed range. This is a widely used error code. See the individual
+ ioctl requests for specific causes.</entry>
+ </row>
+ <row>
+ <entry>ENODEV</entry>
+ <entry>Device not found or was removed.</entry>
+ </row>
+ <row>
+ <entry>ENOMEM</entry>
+ <entry>There's not enough memory to handle the desired operation.</entry>
+ </row>
+ <row>
+ <entry>ENOTTY</entry>
+ <entry>The ioctl is not supported by the driver, actually meaning that
+ the required functionality is not available, or the file
+ descriptor is not for a media device.</entry>
+ </row>
+ <row>
+ <entry>ENOSPC</entry>
+ <entry>On USB devices, the stream ioctl's can return this error, meaning
+ that this request would overcommit the usb bandwidth reserved
+ for periodic transfers (up to 80% of the USB bandwidth).</entry>
+ </row>
+ <row>
+ <entry>EPERM</entry>
+ <entry>Permission denied. Can be returned if the device needs write
+ permission, or some special capabilities is needed
+ (e. g. root)</entry>
+ </row>
+ </tbody>
+ </tgroup>
+<para>Note 1: ioctls may return other error codes. Since errors may have side
+effects such as a driver reset, applications should abort on unexpected errors.
+<para>Note 2: Request-specific error codes are listed in the individual
+requests descriptions.</para>