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The new ioctl USBTMC_IOCTL_WRITE sends a generic message to bulk OUT. This ioctl is used for vendor specific or asynchronous I/O as well. The message is split into chunks of 4k (page size). Message size is aligned to 32 bit boundaries. With flag USBTMC_FLAG_ASYNC the ioctl is non blocking. With flag USBTMC_FLAG_APPEND additional urbs are queued and out_status/out_transfer_size is not reset. EPOLLOUT | EPOLLWRNORM is signaled when all submitted urbs are completed. Flush flying urbs when file handle is closed or device is suspended or reset. This ioctl does not support compatibility for 32 bit applications running on 64 bit systems. However all other convenient ioctls of the USBTMC driver can still be used in 32 bit applications as well. Note that 32 bit applications running on 32 bit target systems are not affected by this limitation. Signed-off-by: Guido Kiener <guido.kiener@rohde-schwarz.com> Reviewed-by: Steve Bayless <steve_bayless@keysight.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.