Re: [PATCH V6] serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers

Stephen Warren
2014-04-21T19:45:21Z

On 04/17/2014 12:06 AM, Yoshihiro YUNOMAE wrote:
> Add tunable RX interrupt trigger I/F of FIFO buffers.
> Serial devices are used as not only message communication devices but control
> or sending communication devices. For the latter uses, normally small data
> will be exchanged, so user applications want to receive data unit as soon as
> possible for real-time tendency. If we have a sensor which sends a 1 byte data
> each time and must control a device based on the sensor feedback, the RX
> interrupt should be triggered for each data.
>
> According to HW specification of serial UART devices, RX interrupt trigger
> can be changed, but the trigger is hard-coded. For example, RX interrupt trigger
> in 16550A can be set to 1, 4, 8, or 14 bytes for HW, but current driver sets
> the trigger to only 8bytes.
>
> This patch makes some devices change RX interrupt trigger from userland.

Reviewed-by: Stephen Warren <swarren@nvidia.com>