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drivers: PL011: replace UART_MIS reading with _RIS & _IMSC 

The PL011 register UART_MIS is actually a bitwise AND of the
UART_RIS and the UART_MISC register.
Since the SBSA UART does not include the _MIS register, use the
two separate registers to get the same behaviour. Since we are
inside the spinlock and we read the _IMSC register only once, there
should be no race issue.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andre Przywara 2015-05-21 17:26:19 +01:00 committed by Greg Kroah-Hartman
parent 3873e2d7f6
commit 075167ed71
1 changed files with 4 additions and 2 deletions
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6
drivers/tty/serial/amba-pl011.c
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@ -1322,11 +1322,13 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
struct uart_amba_port *uap = dev_id; struct uart_amba_port *uap = dev_id;
unsigned long flags; unsigned long flags;
unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT; unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
u16 imsc;
int handled = 0; int handled = 0;
unsigned int dummy_read; unsigned int dummy_read;
spin_lock_irqsave(&uap->port.lock, flags); spin_lock_irqsave(&uap->port.lock, flags);
status = readw(uap->port.membase + UART011_MIS); imsc = readw(uap->port.membase + UART011_IMSC);
status = readw(uap->port.membase + UART011_RIS) & imsc;
if (status) { if (status) {
do { do {
if (uap->vendor->cts_event_workaround) { if (uap->vendor->cts_event_workaround) {
@ -1361,7 +1363,7 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
if (pass_counter-- == 0) if (pass_counter-- == 0)
break; break;
status = readw(uap->port.membase + UART011_MIS); status = readw(uap->port.membase + UART011_RIS) & imsc;
} while (status != 0); } while (status != 0);
handled = 1; handled = 1;
} }