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Commit 6e2f03e2 authored by Ivan Mikhaylov's avatar Ivan Mikhaylov Committed by Michael Ellerman
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powerpc/[booke|4xx]: Don't clobber TCR[WP] when setting TCR[DIE] 



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: default avatarIvan Mikhaylov <ivan@de.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 20975a0a

arch/powerpc/kernel/time.c

+11 −3
Original line number Diff line number Diff line
@@ -739,12 +739,20 @@ 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)