This partially reverts commit f6f586102add. The code added by that commit containted math overflow for 32-bit archs. In addition, the approach used in it is unnecessarily complicated requiring a dedicated timer just for notemt. A simpler approach for providing UART_CAP_NOTEMT already exists (patches 1-2): https://lore.kernel.org/linux-serial/20220411083321.9131-3-ilpo.jarvinen@xxxxxxxxxxxxxxx/T/#u Thus, simply revert the UART_CAP_NOTEMT change for now. There were two driver changes within the patch series adding UART_CAP_NOTEMT taking advantage of the newly added flag. This does not revert the driver changes and therefore also UART_CAP_NOTEMT define has to remain. UART_CAP_NOTEMT remains no-op until support is again added. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx> --- drivers/tty/serial/8250/8250_port.c | 76 +---------------------------- include/linux/serial_8250.h | 2 - 2 files changed, 2 insertions(+), 76 deletions(-) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index c1f24e88ef09..33bd062140c9 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -571,21 +571,8 @@ static void serial8250_clear_fifos(struct uart_8250_port *p) } } -static inline void serial8250_em485_update_temt_delay(struct uart_8250_port *p, - unsigned int cflag, unsigned int baud) -{ - unsigned int bits; - - if (!p->em485) - return; - - bits = tty_get_frame_size(cflag); - p->em485->no_temt_delay = DIV_ROUND_UP(bits * NSEC_PER_SEC, baud); -} - static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t); static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t); -static enum hrtimer_restart serial8250_em485_handle_no_temt(struct hrtimer *t); void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p) { @@ -644,16 +631,6 @@ static int serial8250_em485_init(struct uart_8250_port *p) HRTIMER_MODE_REL); hrtimer_init(&p->em485->start_tx_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); - - if (p->capabilities & UART_CAP_NOTEMT) { - struct tty_struct *tty = p->port.state->port.tty; - - serial8250_em485_update_temt_delay(p, tty->termios.c_cflag, - tty_get_baud_rate(tty)); - hrtimer_init(&p->em485->no_temt_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); - p->em485->no_temt_timer.function = &serial8250_em485_handle_no_temt; - } - p->em485->stop_tx_timer.function = &serial8250_em485_handle_stop_tx; p->em485->start_tx_timer.function = &serial8250_em485_handle_start_tx; p->em485->port = p; @@ -685,7 +662,6 @@ void serial8250_em485_destroy(struct uart_8250_port *p) hrtimer_cancel(&p->em485->start_tx_timer); hrtimer_cancel(&p->em485->stop_tx_timer); - hrtimer_cancel(&p->em485->no_temt_timer); kfree(p->em485); p->em485 = NULL; @@ -1528,11 +1504,6 @@ static void start_hrtimer_ms(struct hrtimer *hrt, unsigned long msec) hrtimer_start(hrt, ms_to_ktime(msec), HRTIMER_MODE_REL); } -static void start_hrtimer_ns(struct hrtimer *hrt, unsigned long nsec) -{ - hrtimer_start(hrt, ns_to_ktime(nsec), HRTIMER_MODE_REL); -} - static void __stop_tx_rs485(struct uart_8250_port *p) { struct uart_8250_em485 *em485 = p->em485; @@ -1564,33 +1535,14 @@ static inline void __stop_tx(struct uart_8250_port *p) if (em485) { unsigned char lsr = serial_in(p, UART_LSR); - - p->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; - /* - * To provide required timing and allow FIFO transfer, + * To provide required timeing and allow FIFO transfer, * __stop_tx_rs485() must be called only when both FIFO and * shift register are empty. It is for device driver to enable * interrupt on TEMT. */ - if ((lsr & BOTH_EMPTY) != BOTH_EMPTY) { - if (!(p->capabilities & UART_CAP_NOTEMT)) - /* __stop_tx will be called again once TEMT triggers */ - return; - - if (!(lsr & UART_LSR_THRE)) - /* __stop_tx will be called again once THRE triggers */ - return; - - /* - * On devices with no TEMT interrupt available, start - * a timer for a byte time. The timer will recall - * __stop_tx(). - */ - em485->active_timer = &em485->no_temt_timer; - start_hrtimer_ns(&em485->no_temt_timer, em485->no_temt_delay); + if ((lsr & BOTH_EMPTY) != BOTH_EMPTY) return; - } __stop_tx_rs485(p); } @@ -1701,27 +1653,6 @@ static inline void start_tx_rs485(struct uart_port *port) __start_tx(port); } -static enum hrtimer_restart serial8250_em485_handle_no_temt(struct hrtimer *t) -{ - struct uart_8250_em485 *em485; - struct uart_8250_port *p; - unsigned long flags; - - em485 = container_of(t, struct uart_8250_em485, no_temt_timer); - p = em485->port; - - serial8250_rpm_get(p); - spin_lock_irqsave(&p->port.lock, flags); - if (em485->active_timer == &em485->no_temt_timer) { - em485->active_timer = NULL; - __stop_tx(p); - } - - spin_unlock_irqrestore(&p->port.lock, flags); - serial8250_rpm_put(p); - return HRTIMER_NORESTART; -} - static enum hrtimer_restart serial8250_em485_handle_start_tx(struct hrtimer *t) { struct uart_8250_em485 *em485 = container_of(t, struct uart_8250_em485, @@ -2927,9 +2858,6 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, serial8250_set_divisor(port, baud, quot, frac); - if (up->capabilities & UART_CAP_NOTEMT) - serial8250_em485_update_temt_delay(up, termios->c_cflag, baud); - /* * LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR * is written without DLAB set, this mode will be disabled. diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h index de135852107c..ff84a3ed10ea 100644 --- a/include/linux/serial_8250.h +++ b/include/linux/serial_8250.h @@ -79,9 +79,7 @@ struct uart_8250_ops { struct uart_8250_em485 { struct hrtimer start_tx_timer; /* "rs485 start tx" timer */ struct hrtimer stop_tx_timer; /* "rs485 stop tx" timer */ - struct hrtimer no_temt_timer; /* "rs485 no TEMT interrupt" timer */ struct hrtimer *active_timer; /* pointer to active timer */ - unsigned long no_temt_delay; /* Delay for no_temt_timer */ struct uart_8250_port *port; /* for hrtimer callbacks */ unsigned int tx_stopped:1; /* tx is currently stopped */ }; -- 2.30.2
