On Sat, Jan 8, 2011 at 12:16 AM, Kevin D. Kissell <kevink@xxxxxxxxxxxxx> wrote: > On 01/06/11 23:56, Anoop P A wrote: >> >> On Thu, 2011-01-06 at 15:31 -0800, Kevin D. Kissell wrote: >>> >>> I'm sure I've said this before, and it's in various comments in the SMTC >>> code, but... > > As an aside to this conversation, would it be possible to create a > Documentation/mips/SMTC.txt file that would actually propagate > upstream, so that I'd stop being the sole repository of SMTC folklore? > I only maintain it as a hobby. >> >> Ok. Well thanks much for your detailed explanation. Well I hope I found >> the root cause . smtc_clockevent_init() was overriding irq_hwmask even >> if are using platform specific get_c0_compare_int. With following patch >> everything seems to be working for me. >> ------------------------------------------------------------------------ >> diff --git a/arch/mips/kernel/cevt-smtc.c b/arch/mips/kernel/cevt-smtc.c >> index 2e72d30..a25fc59 100644 >> --- a/arch/mips/kernel/cevt-smtc.c >> +++ b/arch/mips/kernel/cevt-smtc.c >> @@ -310,9 +310,14 @@ int __cpuinit smtc_clockevent_init(void) >> return 0; >> /* >> * And we need the hwmask associated with the c0_compare >> - * vector to be initialized. >> + * vector to be initialized. However incase of platform >> + * specific get_co_compare_int, don't override irq_hwmask >> + * expect platform code to set a valid mask value. >> */ >> - irq_hwmask[irq] = (0x100<< cp0_compare_irq); >> + >> + if (!get_c0_compare_int) >> + irq_hwmask[irq] = (0x100<< cp0_compare_irq); >> + >> if (cp0_timer_irq_installed) >> return 0; >> ----------------------------------------------------------------------- > > I'm still not clear on one point that, to me, is pretty important when > engineering a fix here. Are you, in fact, using the Count/Compare > interrupt system, but having the externalization of the compare > interrupt routed back through an intervening interrupt controller, > or is your timer coming from another source? > > In the former case, I think you're on the right track as to the > possible cause of a problem, but the fix should actually be simpler > and rather more elegant. Why can't you simply see to it that > cp0_compare_irq is set to the right value, either at compile time, > or in your earliest platform initialization of the interrupt controller? > That would be a one-line, inline change and spare us another > cryptic conditional. Yes ,it is first case. http://git.linux-mips.org/?p=linux.git;a=commit;h=38760d40ca61b18b2809e9c28df8b3ff9af8a02b Above mentioned patch enables platforms to utilize 4k timer code with platform specific timer interrupts. cevt-smtc also had ( copied from cevt-r4k) referred code. Given the specific irq support in cevt-smtc we should add support for specific hwmask , IMHO. > > In the later case, you'll presumably be having lots of other problems, > as cevt-smtc.c is intertwined with cevt-r4k.c and the Count/Compare > paradigm. > > Regards, > > Kevin K. > >
