| Message ID | 20240201105557.28043-1-jirislaby@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/2] serial: core: introduce uart_port_tx_flags() | expand |
On Thu, Feb 01, 2024 at 01:05:42PM +0100, Jiri Slaby wrote: > On 01. 02. 24, 11:55, Jiri Slaby (SUSE) wrote: > > Emil reports: > > After updating Linux on an i.MX28 board, serial communication over > > AUART broke. When I TX from the board and measure on the TX pin, it > > seems like the HW fifo is not emptied before the transmission is > > stopped. > > > > MXS performs weird things with stop_tx(). The driver makes it > > conditional on uart_tx_stopped(). > > > > So the driver needs special handling. Pass the brand new UART_TX_NOSTOP > > to uart_port_tx_flags() and handle the stop on its own. > > > > Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org> > > Reported-by: Emil Kronborg <emil.kronborg@protonmail.com> > > Fixes: 2d141e683e9a ("tty: serial: use uart_port_tx() helper") > > Closes: https://lore.kernel.org/all/miwgbnvy3hjpnricubg76ytpn7xoceehwahupy25bubbduu23s@om2lptpa26xw/ > > Am I unable to send a proper patch anymore? > > I forgot to add mxs+arm maintainers: > Cc: Shawn Guo <shawnguo@kernel.org> > Cc: Sascha Hauer <s.hauer@pengutronix.de> > Cc: Pengutronix Kernel Team <kernel@pengutronix.de> > Cc: Fabio Estevam <festevam@gmail.com> > Cc: NXP Linux Team <linux-imx@nxp.com> > Cc: linux-arm-kernel@lists.infradead.org > > I can resend with those fixed, if you prefer... Nah, this is fine, I'll take this as-is, thanks! greg k-h
On Thu, Feb 01, 2024 at 11:55 +0100, Jiri Slaby (SUSE) wrote: > Emil reports: > After updating Linux on an i.MX28 board, serial communication over > AUART broke. When I TX from the board and measure on the TX pin, it > seems like the HW fifo is not emptied before the transmission is > stopped. > > MXS performs weird things with stop_tx(). The driver makes it > conditional on uart_tx_stopped(). > > So the driver needs special handling. Pass the brand new UART_TX_NOSTOP > to uart_port_tx_flags() and handle the stop on its own. > > Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org> > Reported-by: Emil Kronborg <emil.kronborg@protonmail.com> > Fixes: 2d141e683e9a ("tty: serial: use uart_port_tx() helper") > Closes: https://lore.kernel.org/all/miwgbnvy3hjpnricubg76ytpn7xoceehwahupy25bubbduu23s@om2lptpa26xw/ > --- > drivers/tty/serial/mxs-auart.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c > index 3ec725555bcc..4749331fe618 100644 > --- a/drivers/tty/serial/mxs-auart.c > +++ b/drivers/tty/serial/mxs-auart.c > @@ -605,13 +605,16 @@ static void mxs_auart_tx_chars(struct mxs_auart_port *s) > return; > } > > - pending = uart_port_tx(&s->port, ch, > + pending = uart_port_tx_flags(&s->port, ch, UART_TX_NOSTOP, > !(mxs_read(s, REG_STAT) & AUART_STAT_TXFF), > mxs_write(ch, s, REG_DATA)); > if (pending) > mxs_set(AUART_INTR_TXIEN, s, REG_INTR); > else > mxs_clr(AUART_INTR_TXIEN, s, REG_INTR); > + > + if (uart_tx_stopped(&s->port)) > + mxs_auart_stop_tx(&s->port); > } > > static void mxs_auart_rx_char(struct mxs_auart_port *s) > -- > 2.43.0 > Tested on i.MX28. Tested-by: Emil Kronborg <emil.kronborg@protonmail.com>
Am 01.02.24 um 13:05 schrieb Jiri Slaby: > On 01. 02. 24, 11:55, Jiri Slaby (SUSE) wrote: >> Emil reports: >> After updating Linux on an i.MX28 board, serial communication over >> AUART broke. When I TX from the board and measure on the TX pin, it >> seems like the HW fifo is not emptied before the transmission is >> stopped. >> >> MXS performs weird things with stop_tx(). The driver makes it >> conditional on uart_tx_stopped(). >> >> So the driver needs special handling. Pass the brand new UART_TX_NOSTOP >> to uart_port_tx_flags() and handle the stop on its own. >> >> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org> >> Reported-by: Emil Kronborg <emil.kronborg@protonmail.com> >> Fixes: 2d141e683e9a ("tty: serial: use uart_port_tx() helper") >> Closes: >> https://lore.kernel.org/all/miwgbnvy3hjpnricubg76ytpn7xoceehwahupy25bubbduu23s@om2lptpa26xw/ > Tested-by: Stefan Wahren <wahrenst@gmx.net> Thanks
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 536b2581d3e2..55b1f3ba48ac 100644 --- 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 *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 *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 *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. */
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@kernel.org> Cc: Emil Kronborg <emil.kronborg@protonmail.com> --- Notes: [v2] fix/invert the condition include/linux/serial_core.h | 32 +++++++++++++++++++++++++++----- 1 file changed, 27 insertions(+), 5 deletions(-)