On 11/04/2017 22:12, Rodolfo Giometti wrote:
> Multidrop mode differentiates the data characters and the address
> characters. Data is transmitted with the parity bit to 0 and addresses
> are transmitted with the parity bit to 1. However this usually slow
> down communication by adding a delay between the first byte and the
> others.
>
> This patch defines two non-stadard bits PARMD (that enables multidrop)
> and SENDA (that marks the next transmitted byte as address) that can
> be used to completely remove the delay during transmission by
> correctly managing the parity bit generation in hardware.
>
> Signed-off-by: Rodolfo Giometti <giometti@xxxxxxxx>
> ---
> include/linux/tty.h | 2 ++
> include/uapi/asm-generic/termbits.h | 2 ++
> 2 files changed, 4 insertions(+)
>
> diff --git a/include/linux/tty.h b/include/linux/tty.h
> index 83b264c..85238ff 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -166,6 +166,8 @@ struct tty_bufhead {
> #define C_CIBAUD(tty) _C_FLAG((tty), CIBAUD)
> #define C_CRTSCTS(tty) _C_FLAG((tty), CRTSCTS)
> #define C_CMSPAR(tty) _C_FLAG((tty), CMSPAR)
> +#define C_PARMD(tty) _C_FLAG((tty), PARMD)
> +#define C_SENDA(tty) _C_FLAG((tty), SENDA)
>
> #define L_ISIG(tty) _L_FLAG((tty), ISIG)
> #define L_ICANON(tty) _L_FLAG((tty), ICANON)
> diff --git a/include/uapi/asm-generic/termbits.h b/include/uapi/asm-generic/termbits.h
> index 232b478..7e82859 100644
> --- a/include/uapi/asm-generic/termbits.h
> +++ b/include/uapi/asm-generic/termbits.h
> @@ -140,6 +140,8 @@ struct ktermios {
> #define HUPCL 0002000
> #define CLOCAL 0004000
> #define CBAUDEX 0010000
> +#define PARMD 0100000
> +#define SENDA 0200000
> #define BOTHER 0010000
> #define B57600 0010001
> #define B115200 0010002
>
I guess there's a problem with SENDA (bit 16)
It's overlapping with CIBAUD (002003600000 (bits 28,19,18,17,16))
Regards,
Richard
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