The UART can be operated without an irq. In this case a timer is setup that regularily calls altera_uart_interrupt(). The receiving part depends on pp->imr having the bit ALTERA_UART_STATUS_RRDY_MSK set, otherwise altera_uart_rx_chars() is never called. So ensure that the bit gets set (disguised as ALTERA_UART_CONTROL_RRDY_MSK) by not returning early from altera_uart_startup() if port->irq is 0. This doesn't affect the hardware as the ALTERA_UART_CONTROL_RRDY_MSK bit isn't actually written to the control register. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Acked-by: Tobias Klauser <tklauser@distanz.ch> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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.
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