Updating Tim Kryger's e-mail address.
On 25 June 2014 00:20, Wang Nan <wangnan0@xxxxxxxxxx> wrote:
> From: James Hogan <james.hogan@xxxxxxxxxx>
>
> upstream unclusion
> DTS: DTS2014060600056
> directory: cherry-pick
>
> ----------------------------------------
>
> 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@xxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Jiri Slaby <jslaby@xxxxxxx>
> Cc: Tim Kryger <tim.kryger@xxxxxxxxxx>
Tim Kryger <tim.kryger@xxxxxxxxx>
> Cc: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
> Cc: Matt Porter <matt.porter@xxxxxxxxxx>
> Cc: Markus Mayer <markus.mayer@xxxxxxxxxx>
> Tested-by: Tim Kryger <tim.kryger@xxxxxxxxxx>
> Tested-by: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
> Tested-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/tty/serial/8250/8250_dw.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> index 1b55923..345b5dd 100644
> --- a/drivers/tty/serial/8250/8250_dw.c
> +++ b/drivers/tty/serial/8250/8250_dw.c
> @@ -92,7 +92,8 @@ 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));
> @@ -121,7 +122,8 @@ 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));
> --
> 1.8.4
>
--
Markus Mayer
Broadcom Landing Team
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