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Re: plat_timer_setup, mips_timer_ack, etc.

To: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Subject: Re: plat_timer_setup, mips_timer_ack, etc.
From: Ralf Baechle <ralf@linux-mips.org>
Date: Wed, 17 Oct 2007 18:40:12 +0100
Cc: Atsushi Nemoto <anemo@mba.ocn.ne.jp>, linux-mips@linux-mips.org
In-reply-to: <471639AC.8080301@ru.mvista.com>
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References: <20071017.005211.108739735.anemo@mba.ocn.ne.jp> <20071016163610.GA25794@linux-mips.org> <20071017.020113.63743059.anemo@mba.ocn.ne.jp> <20071017162837.GA5491@linux-mips.org> <471639AC.8080301@ru.mvista.com>
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On Wed, Oct 17, 2007 at 08:34:52PM +0400, Sergei Shtylyov wrote:

> >>$ git-grep mips_timer_ack arch/mips
> >>arch/mips/dec/time.c:   mips_timer_ack = dec_timer_ack;
> >>arch/mips/jmr3927/rbhma3100/setup.c:    mips_timer_ack = 
> >>jmr3927_timer_ack;
> 
>    TX3927 has three channel timer of which only channel 0 is used to 
> implement a clocksource -- however, clocksource code whould also need to be 
> changed since it's now jiffy-based and HRT doesn't tolerate this -- of 
> course, if anybody still cared about this boards
> 
> >>arch/mips/philips/pnx8550/common/time.c:        mips_timer_ack = 
> >>timer_ack;
> 
>    Here we have a case of a vendor abusing the count/compare register and 
> also adding 3 more of them. One pair can be used for clockevents, the other 
> for clocksource (its compare reg. being programmed to all ones).

Well, the TX3900 series is a bit of a frankenprocessor series.  Like take
32-bits from here, a limb from the R3000 and TLB from that other processor
and at the end shock it all well - at TTL levels that is ;-)  So it's not
quite obvious what to expect from that beast.

My question was mostly about the jmr3927 build failing with an undefined
reference to MIPS_CPU_IRQ_BASE.  For most other systems failing with the
same issue it made sense to glue that by converting the platform to
irq_cpu.  But if no device including the cp0 compare interrupt is directly
wired to the cp0 interrupt controller then enabling that doesn't make too
much sense.  So I guess jmr3927 and a hand full of other systems want a
different fix.

  Ralf

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