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| author | Ivan Mikhaylov <ivan@de.ibm.com> | 2017-05-19 18:47:05 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-13 19:48:12 +0200 |
| commit | 7ba7c8222b87993f549910b06e230564197b6e03 (patch) | |
| tree | 3b0bdf9399875c1bbcfbb0de41df6ca27d369163 | |
| parent | b2a40eaef694b35ae39f1924b3bee95595676e25 (diff) | |
| download | linux-stable-7ba7c8222b87993f549910b06e230564197b6e03.tar.gz linux-stable-7ba7c8222b87993f549910b06e230564197b6e03.tar.bz2 linux-stable-7ba7c8222b87993f549910b06e230564197b6e03.zip | |
powerpc/[booke|4xx]: Don't clobber TCR[WP] when setting TCR[DIE]
[ Upstream commit 6e2f03e292ef46eed2b31b0a344a91d514f9cd81 ]
Prevent a kernel panic caused by unintentionally clearing TCR watchdog
bits. At this point in the kernel boot, the watchdog may have already
been enabled by u-boot. The original code's attempt to write to the TCR
register results in an inadvertent clearing of the watchdog
configuration bits, causing the 476 to reset.
Signed-off-by: Ivan Mikhaylov <ivan@de.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/powerpc/kernel/time.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index f1d7e996e673..ab7b661b6da3 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -719,12 +719,20 @@ static int __init get_freq(char *name, int cells, unsigned long *val) static void start_cpu_decrementer(void) { #if defined(CONFIG_BOOKE) || defined(CONFIG_40x) + unsigned int tcr; + /* Clear any pending timer interrupts */ mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS); - /* Enable decrementer interrupt */ - mtspr(SPRN_TCR, TCR_DIE); -#endif /* defined(CONFIG_BOOKE) || defined(CONFIG_40x) */ + tcr = mfspr(SPRN_TCR); + /* + * The watchdog may have already been enabled by u-boot. So leave + * TRC[WP] (Watchdog Period) alone. + */ + tcr &= TCR_WP_MASK; /* Clear all bits except for TCR[WP] */ + tcr |= TCR_DIE; /* Enable decrementer */ + mtspr(SPRN_TCR, tcr); +#endif } void __init generic_calibrate_decr(void) |