how do I block all IRQ's during short (5ms) frame data transfer

Question

I am an old hand with hardware and device drivers and used much earlier Linux versions for hardware control. I am recently back in the game of Linux and device control using embedded processing and have discovered a lot has changed in the Linux world (for the better). However, I am struggling with a hardware control issue involving a very fast SPI-based frame data transfer kernel module that needs to turn of all interrupts for a short time-frame (5msec) to insure proper data transfer timing for the data frame. In the 'old days' of Linux one would use a save_flags - cli() - sti() framework to disable interrupts for the critical section. What is the simplest way to accomplish this within the new (2.6.33 and newer) Linux IRQ control framework.

Scott

Answer 1

The modern equivalents are local_irq_disable(), local_irq_enable(), local_irq_save() and local_irq_restore(). However, doing so for such a long time period (and make no mistake, at modern CPU speeds 5 ms is a long time) is considered pretty antisocial.

Be aware also that modern machines have SMIs (System Management Interrupts) which can't be masked and which can take over the CPU for a distressing length of time, so your code might need to handle that case.

The kernel these days is preemptable and has high-resolution timers for kernel code - your code may be able to use these instead (see include/linux/hrtimer.h).