Messages in this thread Patch in this message | | | Date | Mon, 9 Dec 2013 16:42:23 -0800 | Subject | Re: [PATCH v2] serial: 8250_dw: Improve unwritable LCR workaround | From | Tim Kryger <> |
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On Fri, Dec 6, 2013 at 4:59 PM, James Hogan <james.hogan@imgtec.com> wrote:
> It appears to work with ~0x20 too, and the workaround isn't getting hit (only > tested boot and logging in - nothing fancy). I think having the printks in > this code with the console directed at the serial must have caused > resursion/busy problems somehow.
James,
I tested tested the code you proposed (cleaned up to avoid magic numbers) on my hardware and it works fine.
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index 4658e3e..5f096c7 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -96,7 +96,8 @@ 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)); @@ -132,7 +133,8 @@ 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));
Would you mind posting this for proper review so we can get the fix in?
Thanks, Tim Kryger
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