[PATCH v2 0/5] tty: fixes on top of summer cleanup

[PATCH v2 0/5] tty: fixes on top of summer cleanup

[Jiri Slaby (SUSE)]

These are fixes which were suggested or popped out of the summer cleanup
series.

For v1..v2 diff, see the comments in respective patches.

Jiri Slaby (SUSE) (5):
  serial: 8250: extract serial8250_init_mctrl()
  serial: 8250: extract serial8250_iir_txen_test()
  serial: 8250: rename lsr_TEMT, iir_NOINT to lowercase
  serial: 8250: document doubled "type == PORT_8250_CIR" check
  tty: fix tty_port_tty_*hangup() kernel-doc

 Documentation/driver-api/tty/tty_port.rst |  5 +-
 drivers/tty/serial/8250/8250_core.c       |  2 +
 drivers/tty/serial/8250/8250_port.c       | 60 ++++++++++++++---------
 drivers/tty/tty_port.c                    |  5 --
 include/linux/tty_port.h                  |  9 ++++
 5 files changed, 50 insertions(+), 31 deletions(-)

-- 
2.50.0

[PATCH v2 1/5] serial: 8250: extract serial8250_init_mctrl()

[Jiri Slaby (SUSE)]

After commit 795158691cc0 ("serial: 8250: extract
serial8250_initialize()"), split serial8250_initialize() even more --
the mctrl part of this code can be separated into
serial8250_init_mctrl() -- done now.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
---
[v2]
* use port-> directly.
* do not remove curly braces.
Both rebase errors -- noticed by Andy.
---
 drivers/tty/serial/8250/8250_port.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 48c30e158cb8..0f85a2f292fc 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2216,15 +2216,8 @@ static void serial8250_THRE_test(struct uart_port *port)
 		up->bugs |= UART_BUG_THRE;
 }
 
-static void serial8250_initialize(struct uart_port *port)
+static void serial8250_init_mctrl(struct uart_port *port)
 {
-	struct uart_8250_port *up = up_to_u8250p(port);
-	unsigned long flags;
-	bool lsr_TEMT, iir_NOINT;
-
-	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
-
-	uart_port_lock_irqsave(port, &flags);
 	if (port->flags & UPF_FOURPORT) {
 		if (!port->irq)
 			port->mctrl |= TIOCM_OUT1;
@@ -2235,6 +2228,18 @@ static void serial8250_initialize(struct uart_port *port)
 	}
 
 	serial8250_set_mctrl(port, port->mctrl);
+}
+
+static void serial8250_initialize(struct uart_port *port)
+{
+	struct uart_8250_port *up = up_to_u8250p(port);
+	unsigned long flags;
+	bool lsr_TEMT, iir_NOINT;
+
+	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
+
+	uart_port_lock_irqsave(port, &flags);
+	serial8250_init_mctrl(port);
 
 	/*
 	 * Serial over Lan (SoL) hack:
-- 
2.50.0

[PATCH v2 2/5] serial: 8250: extract serial8250_iir_txen_test()

[Jiri Slaby (SUSE)]

After commit 795158691cc0 ("serial: 8250: extract
serial8250_initialize()"), split serial8250_initialize() even more --
the TX enable test part of this code can be separated into
serial8250_iir_txen_test().

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/tty/serial/8250/8250_port.c | 49 ++++++++++++++++-------------
 1 file changed, 28 insertions(+), 21 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 0f85a2f292fc..5bb0ca04da55 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2230,16 +2230,19 @@ static void serial8250_init_mctrl(struct uart_port *port)
 	serial8250_set_mctrl(port, port->mctrl);
 }
 
-static void serial8250_initialize(struct uart_port *port)
+static void serial8250_iir_txen_test(struct uart_port *port)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
-	unsigned long flags;
 	bool lsr_TEMT, iir_NOINT;
 
-	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
+	if (port->quirks & UPQ_NO_TXEN_TEST)
+		return;
 
-	uart_port_lock_irqsave(port, &flags);
-	serial8250_init_mctrl(port);
+	/* Do a quick test to see if we receive an interrupt when we enable the TX irq. */
+	serial_port_out(port, UART_IER, UART_IER_THRI);
+	lsr_TEMT = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;
+	iir_NOINT = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;
+	serial_port_out(port, UART_IER, 0);
 
 	/*
 	 * Serial over Lan (SoL) hack:
@@ -2247,26 +2250,30 @@ static void serial8250_initialize(struct uart_port *port)
 	 * Lan.  Those chips take a longer time than a normal serial device to signalize that a
 	 * transmission data was queued. Due to that, the above test generally fails. One solution
 	 * would be to delay the reading of iir. However, this is not reliable, since the timeout is
-	 * variable. So, let's just don't test if we receive TX irq.  This way, we'll never enable
-	 * UART_BUG_TXEN.
+	 * variable. So, in case of UPQ_NO_TXEN_TEST, let's just don't test if we receive TX irq.
+	 * This way, we'll never enable UART_BUG_TXEN.
 	 */
-	if (!(port->quirks & UPQ_NO_TXEN_TEST)) {
-		/* Do a quick test to see if we receive an interrupt when we enable the TX irq. */
-		serial_port_out(port, UART_IER, UART_IER_THRI);
-		lsr_TEMT = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;
-		iir_NOINT = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;
-		serial_port_out(port, UART_IER, 0);
-
-		if (lsr_TEMT && iir_NOINT) {
-			if (!(up->bugs & UART_BUG_TXEN)) {
-				up->bugs |= UART_BUG_TXEN;
-				dev_dbg(port->dev, "enabling bad tx status workarounds\n");
-			}
-		} else {
-			up->bugs &= ~UART_BUG_TXEN;
+	if (lsr_TEMT && iir_NOINT) {
+		if (!(up->bugs & UART_BUG_TXEN)) {
+			up->bugs |= UART_BUG_TXEN;
+			dev_dbg(port->dev, "enabling bad tx status workarounds\n");
 		}
+		return;
 	}
 
+	/* FIXME: why is this needed? */
+	up->bugs &= ~UART_BUG_TXEN;
+}
+
+static void serial8250_initialize(struct uart_port *port)
+{
+	unsigned long flags;
+
+	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
+
+	uart_port_lock_irqsave(port, &flags);
+	serial8250_init_mctrl(port);
+	serial8250_iir_txen_test(port);
 	uart_port_unlock_irqrestore(port, flags);
 }
 
-- 
2.50.0

[PATCH v2 3/5] serial: 8250: rename lsr_TEMT, iir_NOINT to lowercase

[Jiri Slaby (SUSE)]

There are already variables like 'iir_noint1' and 'iir_noint2'. Follow
the preexisting lowercase naming of variables. So s/lsr_TEMT/lsr_temt/
and 'iir_NOINT' likewise.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 drivers/tty/serial/8250/8250_port.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 5bb0ca04da55..7eddcab318b4 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2233,15 +2233,15 @@ static void serial8250_init_mctrl(struct uart_port *port)
 static void serial8250_iir_txen_test(struct uart_port *port)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
-	bool lsr_TEMT, iir_NOINT;
+	bool lsr_temt, iir_noint;
 
 	if (port->quirks & UPQ_NO_TXEN_TEST)
 		return;
 
 	/* Do a quick test to see if we receive an interrupt when we enable the TX irq. */
 	serial_port_out(port, UART_IER, UART_IER_THRI);
-	lsr_TEMT = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;
-	iir_NOINT = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;
+	lsr_temt = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;
+	iir_noint = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;
 	serial_port_out(port, UART_IER, 0);
 
 	/*
@@ -2253,7 +2253,7 @@ static void serial8250_iir_txen_test(struct uart_port *port)
 	 * variable. So, in case of UPQ_NO_TXEN_TEST, let's just don't test if we receive TX irq.
 	 * This way, we'll never enable UART_BUG_TXEN.
 	 */
-	if (lsr_TEMT && iir_NOINT) {
+	if (lsr_temt && iir_noint) {
 		if (!(up->bugs & UART_BUG_TXEN)) {
 			up->bugs |= UART_BUG_TXEN;
 			dev_dbg(port->dev, "enabling bad tx status workarounds\n");
-- 
2.50.0

[PATCH v2 4/5] serial: 8250: document doubled "type == PORT_8250_CIR" check

[Jiri Slaby (SUSE)]

The check for "port.type == PORT_8250_CIR" is present twice in
serial8250_register_8250_port(). The latter was already tried to be
dropped by 1104321a7b3b ("serial: Delete dead code for CIR serial
ports") and then reverted by 9527b82ae3af ("Revert "serial: Delete dead
code for CIR serial ports"").

Document this weirdness with a reason.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Link: https://lore.kernel.org/all/aFcDOx1bdB34I5hS@surfacebook.localdomain/
---
 drivers/tty/serial/8250/8250_core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index a6ecb8575da4..feb920c5b2e8 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -717,6 +717,7 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
 		nr_uarts++;
 	}
 
+	/* Check if it is CIR already. We check this below again, see there why. */
 	if (uart->port.type == PORT_8250_CIR) {
 		ret = -ENODEV;
 		goto unlock;
@@ -815,6 +816,7 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
 	if (up->dl_write)
 		uart->dl_write = up->dl_write;
 
+	/* Check the type (again)! It might have changed by the port.type assignment above. */
 	if (uart->port.type != PORT_8250_CIR) {
 		if (uart_console_registered(&uart->port))
 			pm_runtime_get_sync(uart->port.dev);
-- 
2.50.0

[PATCH v2 5/5] tty: fix tty_port_tty_*hangup() kernel-doc

[Jiri Slaby (SUSE)]

The commit below added a new helper, but omitted to move (and add) the
corressponding kernel-doc. Do it now.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Fixes: 2b5eac0f8c6e ("tty: introduce and use tty_port_tty_vhangup() helper")
Link: https://lore.kernel.org/all/b23d566c-09dc-7374-cc87-0ad4660e8b2e@linux.intel.com/
Reported-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
---
 Documentation/driver-api/tty/tty_port.rst | 5 +++--
 drivers/tty/tty_port.c                    | 5 -----
 include/linux/tty_port.h                  | 9 +++++++++
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/Documentation/driver-api/tty/tty_port.rst b/Documentation/driver-api/tty/tty_port.rst
index 5cb90e954fcf..504a353f2682 100644
--- a/Documentation/driver-api/tty/tty_port.rst
+++ b/Documentation/driver-api/tty/tty_port.rst
@@ -42,9 +42,10 @@ TTY Refcounting
 TTY Helpers
 -----------
 
+.. kernel-doc::  include/linux/tty_port.h
+   :identifiers: tty_port_tty_hangup tty_port_tty_vhangup
 .. kernel-doc::  drivers/tty/tty_port.c
-   :identifiers: tty_port_tty_hangup tty_port_tty_wakeup
-
+   :identifiers: tty_port_tty_wakeup
 
 Modem Signals
 -------------
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 903eebdbe12d..5b4d5fb99a59 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -391,11 +391,6 @@ void tty_port_hangup(struct tty_port *port)
 }
 EXPORT_SYMBOL(tty_port_hangup);
 
-/**
- * tty_port_tty_hangup - helper to hang up a tty
- * @port: tty port
- * @check_clocal: hang only ttys with %CLOCAL unset?
- */
 void __tty_port_tty_hangup(struct tty_port *port, bool check_clocal, bool async)
 {
 	struct tty_struct *tty = tty_port_tty_get(port);
diff --git a/include/linux/tty_port.h b/include/linux/tty_port.h
index 021f9a8415c0..332ddb93603e 100644
--- a/include/linux/tty_port.h
+++ b/include/linux/tty_port.h
@@ -251,11 +251,20 @@ static inline int tty_port_users(struct tty_port *port)
 	return port->count + port->blocked_open;
 }
 
+/**
+ * tty_port_tty_hangup - helper to hang up a tty asynchronously
+ * @port: tty port
+ * @check_clocal: hang only ttys with %CLOCAL unset?
+ */
 static inline void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
 {
 	__tty_port_tty_hangup(port, check_clocal, true);
 }
 
+/**
+ * tty_port_tty_vhangup - helper to hang up a tty synchronously
+ * @port: tty port
+ */
 static inline void tty_port_tty_vhangup(struct tty_port *port)
 {
 	__tty_port_tty_hangup(port, false, false);
-- 
2.50.0

Re: [PATCH v2 5/5] tty: fix tty_port_tty_*hangup() kernel-doc

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 2951 bytes --]

On Tue, 24 Jun 2025, Jiri Slaby (SUSE) wrote:

> The commit below added a new helper, but omitted to move (and add) the
> corressponding kernel-doc. Do it now.

corresponding

With that fixed, Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.


> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> Fixes: 2b5eac0f8c6e ("tty: introduce and use tty_port_tty_vhangup() helper")
> Link: https://lore.kernel.org/all/b23d566c-09dc-7374-cc87-0ad4660e8b2e@linux.intel.com/
> Reported-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: linux-doc@vger.kernel.org
> ---
>  Documentation/driver-api/tty/tty_port.rst | 5 +++--
>  drivers/tty/tty_port.c                    | 5 -----
>  include/linux/tty_port.h                  | 9 +++++++++
>  3 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/driver-api/tty/tty_port.rst b/Documentation/driver-api/tty/tty_port.rst
> index 5cb90e954fcf..504a353f2682 100644
> --- a/Documentation/driver-api/tty/tty_port.rst
> +++ b/Documentation/driver-api/tty/tty_port.rst
> @@ -42,9 +42,10 @@ TTY Refcounting
>  TTY Helpers
>  -----------
>  
> +.. kernel-doc::  include/linux/tty_port.h
> +   :identifiers: tty_port_tty_hangup tty_port_tty_vhangup
>  .. kernel-doc::  drivers/tty/tty_port.c
> -   :identifiers: tty_port_tty_hangup tty_port_tty_wakeup
> -
> +   :identifiers: tty_port_tty_wakeup
>  
>  Modem Signals
>  -------------
> diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
> index 903eebdbe12d..5b4d5fb99a59 100644
> --- a/drivers/tty/tty_port.c
> +++ b/drivers/tty/tty_port.c
> @@ -391,11 +391,6 @@ void tty_port_hangup(struct tty_port *port)
>  }
>  EXPORT_SYMBOL(tty_port_hangup);
>  
> -/**
> - * tty_port_tty_hangup - helper to hang up a tty
> - * @port: tty port
> - * @check_clocal: hang only ttys with %CLOCAL unset?
> - */
>  void __tty_port_tty_hangup(struct tty_port *port, bool check_clocal, bool async)
>  {
>  	struct tty_struct *tty = tty_port_tty_get(port);
> diff --git a/include/linux/tty_port.h b/include/linux/tty_port.h
> index 021f9a8415c0..332ddb93603e 100644
> --- a/include/linux/tty_port.h
> +++ b/include/linux/tty_port.h
> @@ -251,11 +251,20 @@ static inline int tty_port_users(struct tty_port *port)
>  	return port->count + port->blocked_open;
>  }
>  
> +/**
> + * tty_port_tty_hangup - helper to hang up a tty asynchronously
> + * @port: tty port
> + * @check_clocal: hang only ttys with %CLOCAL unset?
> + */
>  static inline void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
>  {
>  	__tty_port_tty_hangup(port, check_clocal, true);
>  }
>  
> +/**
> + * tty_port_tty_vhangup - helper to hang up a tty synchronously
> + * @port: tty port
> + */
>  static inline void tty_port_tty_vhangup(struct tty_port *port)
>  {
>  	__tty_port_tty_hangup(port, false, false);
> 

Re: [PATCH v2 1/5] serial: 8250: extract serial8250_init_mctrl()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 2172 bytes --]

On Tue, 24 Jun 2025, Jiri Slaby (SUSE) wrote:

> After commit 795158691cc0 ("serial: 8250: extract
> serial8250_initialize()"), split serial8250_initialize() even more --
> the mctrl part of this code can be separated into
> serial8250_init_mctrl() -- done now.
> 
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Heh, I didn't even realize I was suggesting this :-D but it's good 
nonetheless.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> ---
> [v2]
> * use port-> directly.
> * do not remove curly braces.
> Both rebase errors -- noticed by Andy.
> ---
>  drivers/tty/serial/8250/8250_port.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 48c30e158cb8..0f85a2f292fc 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2216,15 +2216,8 @@ static void serial8250_THRE_test(struct uart_port *port)
>  		up->bugs |= UART_BUG_THRE;
>  }
>  
> -static void serial8250_initialize(struct uart_port *port)
> +static void serial8250_init_mctrl(struct uart_port *port)
>  {
> -	struct uart_8250_port *up = up_to_u8250p(port);
> -	unsigned long flags;
> -	bool lsr_TEMT, iir_NOINT;
> -
> -	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
> -
> -	uart_port_lock_irqsave(port, &flags);
>  	if (port->flags & UPF_FOURPORT) {
>  		if (!port->irq)
>  			port->mctrl |= TIOCM_OUT1;
> @@ -2235,6 +2228,18 @@ static void serial8250_initialize(struct uart_port *port)
>  	}
>  
>  	serial8250_set_mctrl(port, port->mctrl);
> +}
> +
> +static void serial8250_initialize(struct uart_port *port)
> +{
> +	struct uart_8250_port *up = up_to_u8250p(port);
> +	unsigned long flags;
> +	bool lsr_TEMT, iir_NOINT;
> +
> +	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
> +
> +	uart_port_lock_irqsave(port, &flags);
> +	serial8250_init_mctrl(port);
>  
>  	/*
>  	 * Serial over Lan (SoL) hack:
> 

-- 
 i.

Re: [PATCH v2 2/5] serial: 8250: extract serial8250_iir_txen_test()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 3655 bytes --]

On Tue, 24 Jun 2025, Jiri Slaby (SUSE) wrote:

> After commit 795158691cc0 ("serial: 8250: extract
> serial8250_initialize()"), split serial8250_initialize() even more --
> the TX enable test part of this code can be separated into
> serial8250_iir_txen_test().
> 
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> ---
>  drivers/tty/serial/8250/8250_port.c | 49 ++++++++++++++++-------------
>  1 file changed, 28 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 0f85a2f292fc..5bb0ca04da55 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2230,16 +2230,19 @@ static void serial8250_init_mctrl(struct uart_port *port)
>  	serial8250_set_mctrl(port, port->mctrl);
>  }
>  
> -static void serial8250_initialize(struct uart_port *port)
> +static void serial8250_iir_txen_test(struct uart_port *port)
>  {
>  	struct uart_8250_port *up = up_to_u8250p(port);
> -	unsigned long flags;
>  	bool lsr_TEMT, iir_NOINT;
>  
> -	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
> +	if (port->quirks & UPQ_NO_TXEN_TEST)
> +		return;
>  
> -	uart_port_lock_irqsave(port, &flags);
> -	serial8250_init_mctrl(port);
> +	/* Do a quick test to see if we receive an interrupt when we enable the TX irq. */
> +	serial_port_out(port, UART_IER, UART_IER_THRI);
> +	lsr_TEMT = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;
> +	iir_NOINT = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;
> +	serial_port_out(port, UART_IER, 0);
>  
>  	/*
>  	 * Serial over Lan (SoL) hack:
> @@ -2247,26 +2250,30 @@ static void serial8250_initialize(struct uart_port *port)
>  	 * Lan.  Those chips take a longer time than a normal serial device to signalize that a
>  	 * transmission data was queued. Due to that, the above test generally fails. One solution
>  	 * would be to delay the reading of iir. However, this is not reliable, since the timeout is
> -	 * variable. So, let's just don't test if we receive TX irq.  This way, we'll never enable
> -	 * UART_BUG_TXEN.
> +	 * variable. So, in case of UPQ_NO_TXEN_TEST, let's just don't test if we receive TX irq.
> +	 * This way, we'll never enable UART_BUG_TXEN.
>  	 */
> -	if (!(port->quirks & UPQ_NO_TXEN_TEST)) {
> -		/* Do a quick test to see if we receive an interrupt when we enable the TX irq. */
> -		serial_port_out(port, UART_IER, UART_IER_THRI);
> -		lsr_TEMT = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;
> -		iir_NOINT = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;
> -		serial_port_out(port, UART_IER, 0);
> -
> -		if (lsr_TEMT && iir_NOINT) {
> -			if (!(up->bugs & UART_BUG_TXEN)) {
> -				up->bugs |= UART_BUG_TXEN;
> -				dev_dbg(port->dev, "enabling bad tx status workarounds\n");
> -			}
> -		} else {
> -			up->bugs &= ~UART_BUG_TXEN;
> +	if (lsr_TEMT && iir_NOINT) {
> +		if (!(up->bugs & UART_BUG_TXEN)) {
> +			up->bugs |= UART_BUG_TXEN;
> +			dev_dbg(port->dev, "enabling bad tx status workarounds\n");
>  		}
> +		return;
>  	}
>  
> +	/* FIXME: why is this needed? */
> +	up->bugs &= ~UART_BUG_TXEN;
> +}
> +
> +static void serial8250_initialize(struct uart_port *port)
> +{
> +	unsigned long flags;
> +
> +	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
> +
> +	uart_port_lock_irqsave(port, &flags);
> +	serial8250_init_mctrl(port);
> +	serial8250_iir_txen_test(port);
>  	uart_port_unlock_irqrestore(port, flags);
>  }
>  
> 

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

Re: [PATCH v2 1/5] serial: 8250: extract serial8250_init_mctrl()

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 2974 bytes --]

On Tue, 24 Jun 2025, Ilpo Järvinen wrote:

> On Tue, 24 Jun 2025, Jiri Slaby (SUSE) wrote:
> 
> > After commit 795158691cc0 ("serial: 8250: extract
> > serial8250_initialize()"), split serial8250_initialize() even more --
> > the mctrl part of this code can be separated into
> > serial8250_init_mctrl() -- done now.
> > 
> > Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> > Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> 
> Heh, I didn't even realize I was suggesting this :-D but it's good 
> nonetheless.
> 
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> 
> > Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> > ---
> > [v2]
> > * use port-> directly.
> > * do not remove curly braces.
> > Both rebase errors -- noticed by Andy.
> > ---
> >  drivers/tty/serial/8250/8250_port.c | 21 +++++++++++++--------
> >  1 file changed, 13 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> > index 48c30e158cb8..0f85a2f292fc 100644
> > --- a/drivers/tty/serial/8250/8250_port.c
> > +++ b/drivers/tty/serial/8250/8250_port.c
> > @@ -2216,15 +2216,8 @@ static void serial8250_THRE_test(struct uart_port *port)
> >  		up->bugs |= UART_BUG_THRE;
> >  }
> >  
> > -static void serial8250_initialize(struct uart_port *port)
> > +static void serial8250_init_mctrl(struct uart_port *port)
> >  {
> > -	struct uart_8250_port *up = up_to_u8250p(port);
> > -	unsigned long flags;
> > -	bool lsr_TEMT, iir_NOINT;
> > -
> > -	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
> > -
> > -	uart_port_lock_irqsave(port, &flags);
> >  	if (port->flags & UPF_FOURPORT) {

I should have also added what I meant with my earlier suggestion. AFAICT, 
this UPF_FOURPORT thing can only occur if SERIAL_8250_FOURPORT is enabled.

The challenge obviously are the if/else constructs but there are a few 
places that do port->flags & UPF_FOURPORT specific thing and something 
else otherwise. That hw-specific code could be placed into the hw-specific 
8250_fourport.c file if the hw-specific function is made to return true 
if it did match, and the generic code runs otherwise.

I also have no idea why serial/sunsu.c checks UPF_FOURPORT, perhaps that's 
copy-paste in action. :-)

> >  		if (!port->irq)
> >  			port->mctrl |= TIOCM_OUT1;
> > @@ -2235,6 +2228,18 @@ static void serial8250_initialize(struct uart_port *port)
> >  	}
> >  
> >  	serial8250_set_mctrl(port, port->mctrl);
> > +}
> > +
> > +static void serial8250_initialize(struct uart_port *port)
> > +{
> > +	struct uart_8250_port *up = up_to_u8250p(port);
> > +	unsigned long flags;
> > +	bool lsr_TEMT, iir_NOINT;
> > +
> > +	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
> > +
> > +	uart_port_lock_irqsave(port, &flags);
> > +	serial8250_init_mctrl(port);
> >  
> >  	/*
> >  	 * Serial over Lan (SoL) hack:
> > 
> 
> 

-- 
 i.

Re: [PATCH v2 3/5] serial: 8250: rename lsr_TEMT, iir_NOINT to lowercase

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 2017 bytes --]

On Tue, 24 Jun 2025, Jiri Slaby (SUSE) wrote:

> There are already variables like 'iir_noint1' and 'iir_noint2'. Follow
> the preexisting lowercase naming of variables. So s/lsr_TEMT/lsr_temt/
> and 'iir_NOINT' likewise.
> 
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> ---
>  drivers/tty/serial/8250/8250_port.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 5bb0ca04da55..7eddcab318b4 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2233,15 +2233,15 @@ static void serial8250_init_mctrl(struct uart_port *port)
>  static void serial8250_iir_txen_test(struct uart_port *port)
>  {
>  	struct uart_8250_port *up = up_to_u8250p(port);
> -	bool lsr_TEMT, iir_NOINT;
> +	bool lsr_temt, iir_noint;
>  
>  	if (port->quirks & UPQ_NO_TXEN_TEST)
>  		return;
>  
>  	/* Do a quick test to see if we receive an interrupt when we enable the TX irq. */
>  	serial_port_out(port, UART_IER, UART_IER_THRI);
> -	lsr_TEMT = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;
> -	iir_NOINT = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;
> +	lsr_temt = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;
> +	iir_noint = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;
>  	serial_port_out(port, UART_IER, 0);
>  
>  	/*
> @@ -2253,7 +2253,7 @@ static void serial8250_iir_txen_test(struct uart_port *port)
>  	 * variable. So, in case of UPQ_NO_TXEN_TEST, let's just don't test if we receive TX irq.
>  	 * This way, we'll never enable UART_BUG_TXEN.
>  	 */
> -	if (lsr_TEMT && iir_NOINT) {
> +	if (lsr_temt && iir_noint) {
>  		if (!(up->bugs & UART_BUG_TXEN)) {
>  			up->bugs |= UART_BUG_TXEN;
>  			dev_dbg(port->dev, "enabling bad tx status workarounds\n");
> 

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

Re: [PATCH v2 4/5] serial: 8250: document doubled "type == PORT_8250_CIR" check

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 1790 bytes --]

On Tue, 24 Jun 2025, Jiri Slaby (SUSE) wrote:

> The check for "port.type == PORT_8250_CIR" is present twice in
> serial8250_register_8250_port(). The latter was already tried to be
> dropped by 1104321a7b3b ("serial: Delete dead code for CIR serial
> ports") and then reverted by 9527b82ae3af ("Revert "serial: Delete dead
> code for CIR serial ports"").
> 
> Document this weirdness with a reason.
> 
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Cc: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
> Link: https://lore.kernel.org/all/aFcDOx1bdB34I5hS@surfacebook.localdomain/
> ---
>  drivers/tty/serial/8250/8250_core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
> index a6ecb8575da4..feb920c5b2e8 100644
> --- a/drivers/tty/serial/8250/8250_core.c
> +++ b/drivers/tty/serial/8250/8250_core.c
> @@ -717,6 +717,7 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
>  		nr_uarts++;
>  	}
>  
> +	/* Check if it is CIR already. We check this below again, see there why. */
>  	if (uart->port.type == PORT_8250_CIR) {
>  		ret = -ENODEV;
>  		goto unlock;
> @@ -815,6 +816,7 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
>  	if (up->dl_write)
>  		uart->dl_write = up->dl_write;
>  
> +	/* Check the type (again)! It might have changed by the port.type assignment above. */
>  	if (uart->port.type != PORT_8250_CIR) {
>  		if (uart_console_registered(&uart->port))
>  			pm_runtime_get_sync(uart->port.dev);
> 

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

Re: [PATCH v2 1/5] serial: 8250: extract serial8250_init_mctrl()

[Andy Shevchenko]

On Tue, Jun 24, 2025 at 10:06:37AM +0200, Jiri Slaby (SUSE) wrote:
> After commit 795158691cc0 ("serial: 8250: extract
> serial8250_initialize()"), split serial8250_initialize() even more --
> the mctrl part of this code can be separated into
> serial8250_init_mctrl() -- done now.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 2/5] serial: 8250: extract serial8250_iir_txen_test()

[Andy Shevchenko]

On Tue, Jun 24, 2025 at 10:06:38AM +0200, Jiri Slaby (SUSE) wrote:
> After commit 795158691cc0 ("serial: 8250: extract
> serial8250_initialize()"), split serial8250_initialize() even more --
> the TX enable test part of this code can be separated into
> serial8250_iir_txen_test().

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 3/5] serial: 8250: rename lsr_TEMT, iir_NOINT to lowercase

[Andy Shevchenko]

On Tue, Jun 24, 2025 at 10:06:39AM +0200, Jiri Slaby (SUSE) wrote:
> There are already variables like 'iir_noint1' and 'iir_noint2'. Follow
> the preexisting lowercase naming of variables. So s/lsr_TEMT/lsr_temt/
> and 'iir_NOINT' likewise.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 1/5] serial: 8250: extract serial8250_init_mctrl()

[Jiri Slaby]

On 24. 06. 25, 13:15, Ilpo Järvinen wrote:
> On Tue, 24 Jun 2025, Ilpo Järvinen wrote:
> 
>> On Tue, 24 Jun 2025, Jiri Slaby (SUSE) wrote:
>>
>>> After commit 795158691cc0 ("serial: 8250: extract
>>> serial8250_initialize()"), split serial8250_initialize() even more --
>>> the mctrl part of this code can be separated into
>>> serial8250_init_mctrl() -- done now.
>>>
>>> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
>>> Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
>>
>> Heh, I didn't even realize I was suggesting this :-D but it's good
>> nonetheless.
>>
>> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
>>
>>> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
>>> ---
>>> [v2]
>>> * use port-> directly.
>>> * do not remove curly braces.
>>> Both rebase errors -- noticed by Andy.
>>> ---
>>>   drivers/tty/serial/8250/8250_port.c | 21 +++++++++++++--------
>>>   1 file changed, 13 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
>>> index 48c30e158cb8..0f85a2f292fc 100644
>>> --- a/drivers/tty/serial/8250/8250_port.c
>>> +++ b/drivers/tty/serial/8250/8250_port.c
>>> @@ -2216,15 +2216,8 @@ static void serial8250_THRE_test(struct uart_port *port)
>>>   		up->bugs |= UART_BUG_THRE;
>>>   }
>>>   
>>> -static void serial8250_initialize(struct uart_port *port)
>>> +static void serial8250_init_mctrl(struct uart_port *port)
>>>   {
>>> -	struct uart_8250_port *up = up_to_u8250p(port);
>>> -	unsigned long flags;
>>> -	bool lsr_TEMT, iir_NOINT;
>>> -
>>> -	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);
>>> -
>>> -	uart_port_lock_irqsave(port, &flags);
>>>   	if (port->flags & UPF_FOURPORT) {
> 
> I should have also added what I meant with my earlier suggestion. AFAICT,
> this UPF_FOURPORT thing can only occur if SERIAL_8250_FOURPORT is enabled.
> 
> The challenge obviously are the if/else constructs but there are a few
> places that do port->flags & UPF_FOURPORT specific thing and something
> else otherwise. That hw-specific code could be placed into the hw-specific
> 8250_fourport.c file if the hw-specific function is made to return true
> if it did match, and the generic code runs otherwise.

So you can brew a patch for this, right :)? Every time I read some code 
the same you describe, I end up with 10+ patches. I don't want for now :P.

> I also have no idea why serial/sunsu.c checks UPF_FOURPORT, perhaps that's
> copy-paste in action. :-)

Yes, AFAI looked, it was during the switch of sunsu to serial driver. If 
you feel confident (it really appears apparent), drop that too ;).

thanks,
-- 
js
suse labs