Re: [PATCH 29/33] serial: 8250: drop DEBUG_AUTOCONF() macro

Ilpo Järvinen
2025-06-11T13:11:05Z

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On Wed, 11 Jun 2025, Jiri Slaby (SUSE) wrote:

> DEBUG_AUTOCONF() is always disabled (by "#if 0"), so one would need to
> recompile the kernel to use it. And even if they did, they would find
> out it is broken anyway:
> error: variable 'scratch' is used uninitialized whenever 'if' condition is false
>
> Drop it.
>
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
> ---
> drivers/tty/serial/8250/8250_port.c | 39 ++---------------------------
> 1 file changed, 2 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 6363915a1787..e93bfdac3d0e 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -38,15 +38,6 @@
>
> #include "8250.h"
>
> -/*
> - * Debugging.
> - */
> -#if 0
> -#define DEBUG_AUTOCONF(fmt...) printk(fmt)
> -#else
> -#define DEBUG_AUTOCONF(fmt...) do { } while (0)
> -#endif
> -
> /*
> * Here we define the default xmit fifo size used for each type of UART.
> */
> @@ -825,8 +816,6 @@ static void autoconfig_has_efr(struct uart_8250_port *up)
> id3 = serial_icr_read(up, UART_ID3);
> rev = serial_icr_read(up, UART_REV);
>
> - DEBUG_AUTOCONF("950id=%02x:%02x:%02x:%02x ", id1, id2, id3, rev);
> -
> if (id1 == 0x16 && id2 == 0xC9 &&
> (id3 == 0x50 || id3 == 0x52 || id3 == 0x54)) {
> up->port.type = PORT_16C950;
> @@ -850,7 +839,6 @@ static void autoconfig_has_efr(struct uart_8250_port *up)
> * 0x14 - XR16C854.
> */
> id1 = autoconfig_read_divisor_id(up);
> - DEBUG_AUTOCONF("850id=%04x ", id1);
>
> id2 = id1 >> 8;
> if (id2 == 0x10 || id2 == 0x12 || id2 == 0x14) {
> @@ -937,7 +925,6 @@ static void autoconfig_16550a(struct uart_8250_port *up)
> if (serial_in(up, UART_EFR) == 0) {
> serial_out(up, UART_EFR, 0xA8);
> if (serial_in(up, UART_EFR) != 0) {
> - DEBUG_AUTOCONF("EFRv1 ");
> up->port.type = PORT_16650;
> up->capabilities |= UART_CAP_EFR | UART_CAP_SLEEP;
> } else {
> @@ -950,8 +937,6 @@ static void autoconfig_16550a(struct uart_8250_port *up)
>
> if (status1 == UART_IIR_FIFO_ENABLED_16750)
> up->port.type = PORT_16550A_FSL64;
> - else
> - DEBUG_AUTOCONF("Motorola 8xxx DUART ");
> }
> serial_out(up, UART_EFR, 0);
> return;
> @@ -963,7 +948,6 @@ static void autoconfig_16550a(struct uart_8250_port *up)
> */
> serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
> if (serial_in(up, UART_EFR) == 0 && !broken_efr(up)) {
> - DEBUG_AUTOCONF("EFRv2 ");
> autoconfig_has_efr(up);
> return;
> }
> @@ -1026,8 +1010,6 @@ static void autoconfig_16550a(struct uart_8250_port *up)
>
> serial_out(up, UART_LCR, 0);
>
> - DEBUG_AUTOCONF("iir1=%d iir2=%d ", status1, status2);
> -
> if (status1 == UART_IIR_FIFO_ENABLED_16550A &&
> status2 == UART_IIR_FIFO_ENABLED_16750) {
> up->port.type = PORT_16750;
> @@ -1056,17 +1038,10 @@ static void autoconfig_16550a(struct uart_8250_port *up)
> * It's an Xscale.
> * We'll leave the UART_IER_UUE bit set to 1 (enabled).
> */
> - DEBUG_AUTOCONF("Xscale ");
> up->port.type = PORT_XSCALE;
> up->capabilities |= UART_CAP_UUE | UART_CAP_RTOIE;
> return;
> }
> - } else {
> - /*
> - * If we got here we couldn't force the IER_UUE bit to 0.
> - * Log it and continue.
> - */
> - DEBUG_AUTOCONF("Couldn't force IER_UUE to 0 ");
> }
> serial_out(up, UART_IER, iersave);
>
> @@ -1098,9 +1073,6 @@ static void autoconfig(struct uart_8250_port *up)
> if (!port->iobase && !port->mapbase && !port->membase)
> return;
>
> - DEBUG_AUTOCONF("%s: autoconf (0x%04lx, 0x%p): ",
> - port->name, port->iobase, port->membase);
> -
> /*
> * We really do need global IRQs disabled here - we're going to
> * be frobbing the chips IRQ enable register to see if it exists.
> @@ -1147,9 +1119,7 @@ static void autoconfig(struct uart_8250_port *up)
> * We failed; there's nothing here
> */
> uart_port_unlock_irqrestore(port, flags);
> - DEBUG_AUTOCONF("IER test failed (%02x, %02x) ",
> - scratch2, scratch3);
> - goto out;
> + return;
> }
> }
>
> @@ -1171,9 +1141,7 @@ static void autoconfig(struct uart_8250_port *up)
> serial8250_out_MCR(up, save_mcr);
> if (status1 != (UART_MSR_DCD | UART_MSR_CTS)) {
> uart_port_unlock_irqrestore(port, flags);
> - DEBUG_AUTOCONF("LOOP test failed (%02x) ",
> - status1);
> - goto out;
> + return;
> }
> }
>
> @@ -1241,9 +1209,6 @@ static void autoconfig(struct uart_8250_port *up)
> dev_warn(port->dev, "detected caps %08x should be %08x\n",
> old_capabilities, up->capabilities);
> }
> -out:
> - DEBUG_AUTOCONF("iir=%d ", scratch);
> - DEBUG_AUTOCONF("type=%s\n", uart_config[port->type].name);
> }
>
> static void autoconfig_irq(struct uart_8250_port *up)
>

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

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