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can: c_can: fix an interrupt thrash issue with c_can driver
This patch fixes an interrupt thrash issue with c_can driver.
In c_can_isr() function interrupts are disabled and enabled only in
c_can_poll() function. c_can_isr() & c_can_poll() both read the
irqstatus flag. However, irqstatus is always read as 0 in c_can_poll()
because all C_CAN interrupts are disabled in c_can_isr(). This causes
all interrupts to be re-enabled in c_can_poll() which in turn causes
another interrupt since the event is not really handled. This keeps
happening causing a flood of interrupts.
To fix this, read the irqstatus register in isr and use the same cached
value in the poll function.
Cc: stable@kernel.org # 2.6.39+
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>