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serial: 8250: extract serial8250_iir_txen_test()

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After commit 795158691c ("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>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20250624080641.509959-3-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby (SUSE) 2025-06-24 10:06:38 +02:00 committed by Greg Kroah-Hartman
parent 7bdf59c79c
commit ff446fb8c5
1 changed files with 28 additions and 21 deletions
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49
drivers/tty/serial/8250/8250_port.c
View File

@ -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);
}