On Thu, Jan 21, 2010 at 10:26:03PM +0100, Valentin Longchamp wrote:
> The imx CTS trigger level is left at its reset value that is 32
> chars. Since the RX FIFO has 32 entries, when CTS is raised, the
> FIFO already is full. However, some serial port devices first empty
> their TX FIFO before stopping when CTS is raised, resulting in lost
> chars.
>
> This patch sets the trigger level lower so that other chars arrive
> after CTS is raised, there is still room for 16 of them.
>
> Signed-off-by: Valentin Longchamp <valentin.longchamp@xxxxxxx>
> Tested-by: Philippe Rétornaz <philippe.retornaz@xxxxxxx>
If you fix the comment, feel free to add my:
Acked-by: Wolfram Sang <w.sang@xxxxxxxxxxxxxx>
> ---
> drivers/serial/imx.c | 10 +++++++++-
> 1 files changed, 9 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c
> index 18130f1..f7d2da5 100644
> --- a/drivers/serial/imx.c
> +++ b/drivers/serial/imx.c
> @@ -119,7 +119,8 @@
> #define MX2_UCR3_RXDMUXSEL (1<<2) /* RXD Muxed Input Select, on mx2/mx3 */
> #define UCR3_INVT (1<<1) /* Inverted Infrared transmission */
> #define UCR3_BPEN (1<<0) /* Preset registers enable */
> -#define UCR4_CTSTL_32 (32<<10) /* CTS trigger level (32 chars) */
> +#define UCR4_CTSTL_SHF 10 /* CTS trigger level shift */
> +#define UCR4_CTSTL_MASK 0x3F /* CTS trigger is 6 bits wide */
> #define UCR4_INVR (1<<9) /* Inverted infrared reception */
> #define UCR4_ENIRI (1<<8) /* Serial infrared interrupt enable */
> #define UCR4_WKEN (1<<7) /* Wake interrupt enable */
> @@ -590,6 +591,8 @@ static int imx_setup_ufcr(struct imx_port *sport, unsigned int mode)
> return 0;
> }
>
> +#define CTSTL 16
> +
Maybe a comment that it is set to half the buffer size? Dunno...
> static int imx_startup(struct uart_port *port)
> {
> struct imx_port *sport = (struct imx_port *)port;
> @@ -606,6 +609,11 @@ static int imx_startup(struct uart_port *port)
> if (USE_IRDA(sport))
> temp |= UCR4_IRSC;
>
> + /* set the trigger level for CTS to 16 by default
> + */
Make this comment a one-liner. Also remove the "to 16 by default" part as this
value is #defined and, who knows, it may change.
> + temp &= ~(UCR4_CTSTL_MASK << UCR4_CTSTL_SHF);
> + temp |= CTSTL << UCR4_CTSTL_SHF;
> +
> writel(temp & ~UCR4_DREN, sport->port.membase + UCR4);
>
> if (USE_IRDA(sport)) {
--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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