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authorJason Wessel <jason.wessel@windriver.com>2010-05-21 04:04:22 +0200
committerJason Wessel <jason.wessel@windriver.com>2010-05-21 04:04:22 +0200
commitf5316b4aea024da9266d740322a5481657f6ce59 (patch)
tree5888fd0afa54fc3bab2711e583147c4b563836bc /drivers/serial
parentkgdb: core changes to support kdb (diff)
downloadlinux-f5316b4aea024da9266d740322a5481657f6ce59.tar.xz
linux-f5316b4aea024da9266d740322a5481657f6ce59.zip
kgdb,8250,pl011: Return immediately from console poll
The design of the kdb shell requires that every device that can provide input to kdb have a polling routine that exits immediately if there is no character available. This is required in order to get the page scrolling mechanism working. Changing the kernel debugger I/O API to require all polling character routines to exit immediately if there is no data allows the kernel debugger to process multiple input channels. NO_POLL_CHAR will be the return code to the polling routine when ever there is no character available. CC: linux-serial@vger.kernel.org Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Diffstat (limited to 'drivers/serial')
-rw-r--r--drivers/serial/8250.c4
-rw-r--r--drivers/serial/amba-pl011.c6
2 files changed, 5 insertions, 5 deletions
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 2b1ea3d4c4f4..891e1dd65f24 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1891,8 +1891,8 @@ static int serial8250_get_poll_char(struct uart_port *port)
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned char lsr = serial_inp(up, UART_LSR);
- while (!(lsr & UART_LSR_DR))
- lsr = serial_inp(up, UART_LSR);
+ if (!(lsr & UART_LSR_DR))
+ return NO_POLL_CHAR;
return serial_inp(up, UART_RX);
}
diff --git a/drivers/serial/amba-pl011.c b/drivers/serial/amba-pl011.c
index 743ebf5f16da..eb4cb480b93e 100644
--- a/drivers/serial/amba-pl011.c
+++ b/drivers/serial/amba-pl011.c
@@ -342,9 +342,9 @@ static int pl010_get_poll_char(struct uart_port *port)
struct uart_amba_port *uap = (struct uart_amba_port *)port;
unsigned int status;
- do {
- status = readw(uap->port.membase + UART01x_FR);
- } while (status & UART01x_FR_RXFE);
+ status = readw(uap->port.membase + UART01x_FR);
+ if (status & UART01x_FR_RXFE)
+ return NO_POLL_CHAR;
return readw(uap->port.membase + UART01x_DR);
}