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authorThomas Gleixner <tglx@linutronix.de>2007-07-21 11:11:12 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-21 21:37:12 -0400
commit075bcd1f9726b8a1caff86eda06f29f71fb21235 (patch)
tree992a8717dbe7b17fa80cd10f47c3dc639f395aa2
parentdf2edcf3b6ba54d9ffa620e322583cd994a6e54a (diff)
i386: HPET, check if the counter works
Some systems have a HPET which is not incrementing, which leads to a complete hang. Detect it during HPET setup. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/i386/kernel/hpet.c24
1 files changed, 23 insertions, 1 deletions
diff --git a/arch/i386/kernel/hpet.c b/arch/i386/kernel/hpet.c
index 662d7976a9ea..b93310d11950 100644
--- a/arch/i386/kernel/hpet.c
+++ b/arch/i386/kernel/hpet.c
@@ -232,7 +232,8 @@ int __init hpet_enable(void)
232{ 232{
233 unsigned long id; 233 unsigned long id;
234 uint64_t hpet_freq; 234 uint64_t hpet_freq;
235 u64 tmp; 235 u64 tmp, start, now;
236 cycle_t t1;
236 237
237 if (!is_hpet_capable()) 238 if (!is_hpet_capable())
238 return 0; 239 return 0;
@@ -279,6 +280,27 @@ int __init hpet_enable(void)
279 /* Start the counter */ 280 /* Start the counter */
280 hpet_start_counter(); 281 hpet_start_counter();
281 282
283 /* Verify whether hpet counter works */
284 t1 = read_hpet();
285 rdtscll(start);
286
287 /*
288 * We don't know the TSC frequency yet, but waiting for
289 * 200000 TSC cycles is safe:
290 * 4 GHz == 50us
291 * 1 GHz == 200us
292 */
293 do {
294 rep_nop();
295 rdtscll(now);
296 } while ((now - start) < 200000UL);
297
298 if (t1 == read_hpet()) {
299 printk(KERN_WARNING
300 "HPET counter not counting. HPET disabled\n");
301 goto out_nohpet;
302 }
303
282 /* Initialize and register HPET clocksource 304 /* Initialize and register HPET clocksource
283 * 305 *
284 * hpet period is in femto seconds per cycle 306 * hpet period is in femto seconds per cycle