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powerpc/hmi: Fix kernel hang when TB is in error state.

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On TOD/TB errors timebase register stops/freezes until HMI error recovery
gets TOD/TB back into running state. On successful recovery, TB starts
running again and udelay() that relies on TB value continues to function
properly. But in case when HMI fails to recover from TOD/TB errors, the
TB register stay freezed. With TB not running the __delay() function
keeps looping and never return. If __delay() is called while in panic
path then system hangs and never reboots after panic.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Mahesh Salgaonkar
2019-03-05 01:12:19 +05:30
committed by Michael Ellerman
parent 0acb5f6456
commit de269129a4
7 changed files with 49 additions and 1 deletions
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2
arch/powerpc/include/asm/time.h
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@@ -36,6 +36,8 @@ extern unsigned long ppc_proc_freq;
extern unsigned long ppc_tb_freq;
#define DEFAULT_TB_FREQ 125000000UL
extern bool tb_invalid;
struct div_result {
u64 result_high;
u64 result_low;