Re: [PATCH v2] serial: 8250_dw: Improve unwritable LCR workaround

Ezequiel Garcia
2013-12-10T12:11:47Z

Hi Tim, James:

On Mon, Dec 09, 2013 at 04:42:23PM -0800, Tim Kryger wrote:
> On Fri, Dec 6, 2013 at 4:59 PM, James Hogan <james.hogan@imgtec.com> wrote:
>
[..]
> 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?
>

Applying this change fixes all the problems I reported (just did a quick test on
the board I have currently on my desk).

Nice work!
--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com
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