This is a note to let you know that I've just added the patch titled
powerpc/[booke|4xx]: Don't clobber TCR[WP] when setting TCR[DIE]
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-don-t-clobber-tcr-when-setting-tcr.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Apr 9 17:09:24 CEST 2018
From: Ivan Mikhaylov <ivan@xxxxxxxxxx>
Date: Fri, 19 May 2017 18:47:05 +0300
Subject: powerpc/[booke|4xx]: Don't clobber TCR[WP] when setting TCR[DIE]
From: Ivan Mikhaylov <ivan@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/time.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -719,12 +719,20 @@ static int __init get_freq(char *name, i
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)
Patches currently in stable-queue which might be from ivan@xxxxxxxxxx are
queue-4.9/powerpc-don-t-clobber-tcr-when-setting-tcr.patch