Re: What is the right way to setup MIPS timer irq in 2.6.29?

[David Daney <ddaney@caviumnetworks.com>]

David Wuertele wrote:
> I wrote:
> 
>> Has the system timer paradigm changed between 2.6.18 and 2.6.29?
>> I'm trying to update my Broadcom-based embedded system to 2.6.29,
>> and I'm running into problems getting the system timer to run.
> 
> I solved my problem, though I'm still a little unclear about the reasoning.
> 
> The solution was to enable these:
> CONFIG_CEVT_R4K=y
> CONFIG_CSRC_R4K=y
> 
> I also had to define get_c0_compare_int() to return the system timer
> interrupt.  Once I had done these things, start_kernel() calls time_init(),
> which calls mips_clockevent_init() and init_mips_clocksource().
> init_mips_clocksource() calls the init_r4k_clocksource() that was
> enabled with the new config options.  Now my system clock runs like I think it
> should.
> 
> I think I might not need the CEVT components... I'm going to look into that
> next.

No, you do need them.  That is the source of the interrupts.  Using the 
standard cevt-r4k.c you get nice things like the tickless kernel all for 
free.


> But I wish there was some easy to find documentation about why this
> code had to be moved into the arch/mips/cevt-*.c and arch/mips/csrc-*.c
> libraries.
> 

It had to change because the entire Linux time keeping infrastructure 
change to use the generic clock source and clock event system.

David Daney