korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-12-22 10:34:55 +08:00
Code Issues Packages Projects Releases Wiki Activity

serial: pl011: Use cached copy of IMSC register

Browse Source 
Commit 075167ed71 ("drivers: PL011: replace UART_MIS reading with
_RIS & _IMSC") amended this driver's interrupt handler to read the
Raw Interrupt Status (RIS) and Interrupt Mask Set/Clear (IMSC) registers
instead of the Masked Interrupt Status (MIS) register.  The change was
made to attain compatibility with SBSA UARTs which lack the MIS register.

However the IMSC register is cached by the driver.  Using the cached
copy saves one register read per interrupt.

I've tested this change successfully on a BCM2837 (Raspberry Pi CM3).

Cc: Mathias Duckeck <m.duckeck@kunbus.de>
Cc: Phil Elwell <phil@raspberrypi.org>
Cc: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Mark Langsdorf <mlangsdo@redhat.com>
Cc: Naresh Bhat <nbhat@cavium.com>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lukas Wunner 2017-11-25 00:33:27 +01:00 committed by Greg Kroah-Hartman
parent d8dcbdd08c
commit d3a96c9416
1 changed files with 2 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/tty/serial/amba-pl011.c
View File

@ -1480,12 +1480,10 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
struct uart_amba_port *uap = dev_id;
unsigned long flags;
unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
u16 imsc;
int handled = 0;
spin_lock_irqsave(&uap->port.lock, flags);
imsc = pl011_read(uap, REG_IMSC);
status = pl011_read(uap, REG_RIS) & imsc;
status = pl011_read(uap, REG_RIS) & uap->im;
if (status) {
do {
check_apply_cts_event_workaround(uap);
@ -1509,7 +1507,7 @@ static irqreturn_t pl011_int(int irq, void *dev_id)
if (pass_counter-- == 0)
break;
status = pl011_read(uap, REG_RIS) & imsc;
status = pl011_read(uap, REG_RIS) & uap->im;
} while (status != 0);
handled = 1;
}