powerpc/[booke|4xx]: Don't clobber TCR[WP] when setting TCR[DIE] (6e2f03e2) · Commits · 戴 / test

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>

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)

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