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UBUNTU: SAUCE: platform/x86: dell-uart-backlight: replace chars_in_buffer() with flush_chars()

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BugLink: https://bugs.launchpad.net/bugs/2032174

After v6.5, calls tty->driver->ops->chars_in_buffer() may lead to a
deadlock and got soft lockup error. Try using tty->driver->ops->flush_chars()
to archive to same scenario.

There is no functional change, even if uart_flush_chars() doesn't do what
we expected, the driver should be able to keep working, as the backlight
commands is only 3 or 4 bytes short and has little chance to stay in the
queue partially.

Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao@canonical.com>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
This commit is contained in:
Chia-Lin Kao (AceLan)
2023-08-22 11:57:40 +08:00
committed by Paolo Pisati
parent 782b744249
commit 795e5a2ca9
1 changed files with 4 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/platform/x86/dell/dell-uart-backlight.c
+4 -4
View File
@@ -39,7 +39,8 @@ static struct file *ftty;
unsigned int (*io_serial_in)(struct uart_port *p, int offset);
int (*uart_write)(struct tty_struct *tty, const unsigned char *buf, int count);
unsigned int (*uart_chars_in_buffer)(struct tty_struct *tty);
void (*uart_flush_chars)(struct tty_struct *tty);
static bool force;
module_param(force, bool, 0444);
@@ -160,8 +161,7 @@ static int dell_uart_write(struct uart_8250_port *up, __u8 *buf, int len)
tty_port_tty_wakeup(&port->state->port);
tty = tty_port_tty_get(&port->state->port);
actual = uart_write(tty, buf, len);
while (uart_chars_in_buffer(tty))
udelay(10);
uart_flush_chars(tty);
return actual;
}
@@ -401,7 +401,7 @@ static int dell_uart_startup(struct dell_uart_backlight *dell_pdata)
tty = port->state->port.tty;
io_serial_in = port->serial_in;
uart_write = tty->driver->ops->write;
uart_chars_in_buffer = tty->driver->ops->chars_in_buffer;
uart_flush_chars = tty->driver->ops->flush_chars;
return 0;
}