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

Message ID 20250624080641.509959-5-jirislaby@kernel.org
State New
Headers show
Series tty: fixes on top of summer cleanup | expand

Commit Message

Jiri Slaby (SUSE) June 24, 2025, 8:06 a.m. UTC 
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(+)
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Patch

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);