[meta-freescale] imx6Q: sdma produces a large number of interrupts
georgekang03 at gmail.com
Sat Jul 16 06:28:39 PDT 2016
Sometimes, sdma produces a large number of interrupts without a stop, and
Linux kernel might freeze. This situation
happens in kernel with PREEMPT_RT in some specific configuration for
islocpu. Currently, the kernel in my test is
Linux 4.1.15-rt17 and the kernel command line is
console=ttymxc0,115200 root=/dev/mmcblk0p2 rootwait rw nohz_full=3
After booting, the kernel will freeze and the last messages are:
imx-weim 21b8000.weim: Driver registered.
imx-sdma 20ec000.sdma: failed to get firmware from device tree
imx-sdma 20ec000.sdma: initialized
2020000.serial: ttymxc0 at MMIO 0x2020000 (irq = 24, base_baud =
5000000) is a IMX
console [ttymxc0] enabled
random: nonblocking pool is initialized
The last line give me a hint and I find add_interrupt_randomness() from
irq_thread is called continuously
Then I insert a printk in irq_thread(void *data) to identify the interrupt
source for this issue.
It shows 281, which is the interrupt number of sdma, and never stops.
In my root fs, the firmware for sdma does not exist and the number of sdma
interrupt is only two in ordinary booting.
Is there any suggestion to investigate this issue?
Thanks a lot.
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