@@ -95,7 +95,8 @@ static void dw8250_serial_out(struct uart_port *p, int offset, int value)
if (offset == UART_LCR) {
int tries = 1000;
while (tries--) {
- if (value == p->serial_in(p, UART_LCR))
+ unsigned int lcr = p->serial_in(p, UART_LCR);
+ if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
return;
dw8250_force_idle(p);
writeb(value, p->membase + (UART_LCR << p->regshift));
@@ -131,7 +132,8 @@ static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
if (offset == UART_LCR) {
int tries = 1000;
while (tries--) {
- if (value == p->serial_in(p, UART_LCR))
+ unsigned int lcr = p->serial_in(p, UART_LCR);
+ if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
return;
dw8250_force_idle(p);
writel(value, p->membase + (UART_LCR << p->regshift));
This is a note to let you know that I have just added a patch titled serial: 8250_dw: Fix LCR workaround regression to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From e5472b518e20b7671dd9e0e3475e6ca38152d3ea Mon Sep 17 00:00:00 2001 From: James Hogan <james.hogan@imgtec.com> Date: Tue, 10 Dec 2013 22:28:04 +0000 Subject: serial: 8250_dw: Fix LCR workaround regression commit 6979f8d28049879e6147767d93ba6732c8bd94f4 upstream. Commit c49436b657d0 (serial: 8250_dw: Improve unwritable LCR workaround) caused a regression. It added a check that the LCR was written properly to detect and workaround the busy quirk, but the behaviour of bit 5 (UART_LCR_SPAR) differs between IP versions 3.00a and 3.14c per the docs. On older versions this caused the check to fail and it would repeatedly force idle and rewrite the LCR register, causing delays and preventing any input from serial being received. This is fixed by masking out UART_LCR_SPAR before making the comparison. Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Tim Kryger <tim.kryger@linaro.org> Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com> Cc: Matt Porter <matt.porter@linaro.org> Cc: Markus Mayer <markus.mayer@linaro.org> Tested-by: Tim Kryger <tim.kryger@linaro.org> Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com> Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Wang Nan <wangnan0@huawei.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/tty/serial/8250/8250_dw.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) -- 1.9.1