6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx> commit 3ee07964d407411fd578a3bc998de44fd64d266a upstream. And an enum with a flag: UART_TX_NOSTOP. To NOT call __port->ops->stop_tx() when the circular buffer is empty. mxs-uart needs this (see the next patch). Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@xxxxxxxxxx> Cc: stable <stable@xxxxxxxxxx> Tested-by: Emil Kronborg <emil.kronborg@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20240201105557.28043-1-jirislaby@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/serial_core.h | 32 +++++++++++++++++++++++++++----- 1 file changed, 27 insertions(+), 5 deletions(-) --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -748,8 +748,17 @@ struct uart_driver { void uart_write_wakeup(struct uart_port *port); -#define __uart_port_tx(uport, ch, tx_ready, put_char, tx_done, for_test, \ - for_post) \ +/** + * enum UART_TX_FLAGS -- flags for uart_port_tx_flags() + * + * @UART_TX_NOSTOP: don't call port->ops->stop_tx() on empty buffer + */ +enum UART_TX_FLAGS { + UART_TX_NOSTOP = BIT(0), +}; + +#define __uart_port_tx(uport, ch, flags, tx_ready, put_char, tx_done, \ + for_test, for_post) \ ({ \ struct uart_port *__port = (uport); \ struct circ_buf *xmit = &__port->state->xmit; \ @@ -777,7 +786,7 @@ void uart_write_wakeup(struct uart_port if (pending < WAKEUP_CHARS) { \ uart_write_wakeup(__port); \ \ - if (pending == 0) \ + if (!((flags) & UART_TX_NOSTOP) && pending == 0) \ __port->ops->stop_tx(__port); \ } \ \ @@ -812,7 +821,7 @@ void uart_write_wakeup(struct uart_port */ #define uart_port_tx_limited(port, ch, count, tx_ready, put_char, tx_done) ({ \ unsigned int __count = (count); \ - __uart_port_tx(port, ch, tx_ready, put_char, tx_done, __count, \ + __uart_port_tx(port, ch, 0, tx_ready, put_char, tx_done, __count, \ __count--); \ }) @@ -826,8 +835,21 @@ void uart_write_wakeup(struct uart_port * See uart_port_tx_limited() for more details. */ #define uart_port_tx(port, ch, tx_ready, put_char) \ - __uart_port_tx(port, ch, tx_ready, put_char, ({}), true, ({})) + __uart_port_tx(port, ch, 0, tx_ready, put_char, ({}), true, ({})) + +/** + * uart_port_tx_flags -- transmit helper for uart_port with flags + * @port: uart port + * @ch: variable to store a character to be written to the HW + * @flags: %UART_TX_NOSTOP or similar + * @tx_ready: can HW accept more data function + * @put_char: function to write a character + * + * See uart_port_tx_limited() for more details. + */ +#define uart_port_tx_flags(port, ch, flags, tx_ready, put_char) \ + __uart_port_tx(port, ch, flags, tx_ready, put_char, ({}), true, ({})) /* * Baud rate helpers. */
