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According to an old GPL'ed driver at <ftp://ftp.mccdaq.com/downloads/iotech_software/DaqBoard_1000_2000_Series/Linux_driver_kernelv2.4.x/>, The CPLD status register can be checked to make sure that it is ready to accept the next 16-bit word of FPGA firmware data, but that doesn't work on older versions of the CPLD, where a simple delay should be used between successive writes. The current version of the Comedi driver just uses a delay between successive writes. Change it to check for the newer CPLD in the `daqboard2000_load_firmware()`, and change the firmware word writing function `daqboard2000_write_cpld()` to wait for the status bit (`DB2K_CPLD_STATUS_TXREADY`, previously called `DB2K_CPLD_TXDONE`) to be set for newer CPLD, or just delay for older CPLD. Return an error if it times out waiting for the status bit. The wait for the `DB2K_CPLD_STATUS_TXREADY` status bit to be set is performed by new function `daqboard2000_wait_cpld_txready()`, which returns 0 if the status bit is set within 100 microseconds, or `-ETIMEDOUT` if not. Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.