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authorjuhosg <juhosg@3c298f89-4303-0410-b956-a3cf2f4a3e73>2011-11-13 11:26:52 +0000
committerjuhosg <juhosg@3c298f89-4303-0410-b956-a3cf2f4a3e73>2011-11-13 11:26:52 +0000
commit4cc612872a92f33fe0164f0b7762b9f5b2e5c181 (patch)
tree02d1026a16ab6c9e288a8a15ecbe9188e0650889 /target/linux/ar71xx/files
parent5fb5b4483ba809ce225b4bb50a3d42bdc936a397 (diff)
ar71xx: fix occasional kernel hangs during boot on AR934x
The patch taken from the linux-mips mailing list. The Kernel hangs occasionally during boot after "Calibrating delay loop..". This is caused by the c0_compare_int_usable() routine in cevt-r4k.c returning false which causes the system to disable the timer and hang later. The false return happens because the routine is using a series of four calls to irq_disable_hazard() as a delay while it waits for the timer changes to propagate to the cp0 cause register. On newer MIPS cores, like the 74K, the series of irq_disable_hazard() calls turn into ehb instructions and can take as little as a few clock ticks for all 4 instructions. This is not enough of a delay, so the routine thinks the timer is not working. This fix uses up to a max number of cycle counter ticks for the delay and uses back_to_back_c0_hazard() instead of irq_disable_hazard() to handle the hazard condition between cp0 writes and cp0 reads. git-svn-id: svn://svn.openwrt.org/openwrt/trunk@29009 3c298f89-4303-0410-b956-a3cf2f4a3e73
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