path: root/arch/powerpc/platforms/pseries/eeh_driver.c
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authorPaul Mackerras <paulus@samba.org>2007-10-31 22:25:35 +1100
committerPaul Mackerras <paulus@samba.org>2007-11-08 14:15:31 +1100
commit43875cc0a54d936132010e58545269e183741fae (patch)
tree65409e7b9161fcaf8a88b67ebe91ffdb2ad97809 /arch/powerpc/platforms/pseries/eeh_driver.c
parent[POWERPC] Fix switch_slb handling of 1T ESID values (diff)
[POWERPC] Fix off-by-one error in setting decrementer on Book E/4xx (v2)
The decrementer in Book E and 4xx processors interrupts on the transition from 1 to 0, rather than on the 0 to -1 transition as on 64-bit server and 32-bit "classic" (6xx/7xx/7xxx) processors. At the moment we subtract 1 from the count of how many decrementer ticks are required before the next interrupt before putting it into the decrementer, which is correct for server/classic processors, but could possibly cause the interrupt to happen too early on Book E and 4xx if the timebase/decrementer frequency is low. This fixes the problem by making set_dec subtract 1 from the count for server and classic processors, instead of having the callers subtract 1. Since set_dec already had a bunch of ifdefs to handle different processor types, there is no net increase in ugliness. :) Note that calling set_dec(0) may not generate an interrupt on some processors. To make sure that decrementer_set_next_event always calls set_dec with an interval of at least 1 tick, we set min_delta_ns of the decrementer_clockevent to correspond to 2 ticks (2 rather than 1 to compensate for truncations in the conversions between ticks and ns). This also removes a redundant call to set the decrementer to 0x7fffffff - it was already set to that earlier in timer_interrupt. Signed-off-by: Paul Mackerras <paulus@samba.org>
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