Re: [PATCH] x86: fix hpet timer reinit for x86_64

From: Vitaly Mayatskikh
Date: Wed Feb 04 2009 - 06:39:58 EST


At Wed, 04 Feb 2009 13:40:31 +0300, Pavel Emelyanov wrote:
>
> There's a small problem with hpet_rtc_reinit function - it checks
> for the
> hpet_readl(HPET_COUNTER) - hpet_t1_cmp > 0
> to continue increasing both the HPET_T1_CMP (register) and the
> hpet_t1_cmp (variable).
>
> But since the HPET_COUNTER is always 32-bit, if the hpet_t1_cmp
> is 64-bit this condition will always be FALSE once the latter hits
> the 32-bit boundary, and we can have a situation, when we don't
> increase the HPET_T1_CMP register high enough.
>
> The result - timer stops ticking, since HPET_T1_CMP becomes less,
> than the COUNTER and never increased again.
>
> The solution is to cut the upper 32-bit from the hpet_t1_cmp
> variable to make the comparison to HPET_COUNTER correct.

Why not to use u32 as a type for hpet_t1_cmp then?
--
wbr, Vitaly
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