On Mon, Apr 07, 2025 at 08:22:14PM +0300, Andy Shevchenko wrote:
> First of all, using 'mmio' prevents proper implementation of 8-bit accessors.
> Second, it's simply inconsistent with uart8250 set of options. Rename it to
> 'mmio32'. While at it, remove rather misleading comment in the documentation.
> >From now on mmio32 is self-explanatory and pciserial supports not only 32-bit
> MMIO accessors.
>
> Fixes: 3181424aeac2 ("x86/early_printk: Add support for MMIO-based UARTs")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Reviewed-by: Denis Mukhin <dmukhin@xxxxxxxx>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 5 +----
> arch/x86/kernel/early_printk.c | 6 +++---
> 2 files changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 76e538c77e31..d9fd26b95b34 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1407,18 +1407,15 @@
> earlyprintk=serial[,0x...[,baudrate]]
> earlyprintk=ttySn[,baudrate]
> earlyprintk=dbgp[debugController#]
> + earlyprintk=mmio32,membase[,{nocfg|baudrate}]
> earlyprintk=pciserial[,force],bus:device.function[,{nocfg|baudrate}]
> earlyprintk=xdbc[xhciController#]
> earlyprintk=bios
> - earlyprintk=mmio,membase[,{nocfg|baudrate}]
>
> earlyprintk is useful when the kernel crashes before
> the normal console is initialized. It is not enabled by
> default because it has some cosmetic problems.
>
> - Only 32-bit memory addresses are supported for "mmio"
> - and "pciserial" devices.
> -
> Use "nocfg" to skip UART configuration, assume
> BIOS/firmware has configured UART correctly.
>
> diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
> index b70e6e99fb17..dc053641698c 100644
> --- a/arch/x86/kernel/early_printk.c
> +++ b/arch/x86/kernel/early_printk.c
> @@ -424,10 +424,10 @@ static int __init setup_early_printk(char *buf)
> keep = (strstr(buf, "keep") != NULL);
>
> while (*buf != '\0') {
> - if (!strncmp(buf, "mmio", 4)) {
> - early_mmio_serial_init(buf + 4);
> + if (!strncmp(buf, "mmio32", 6)) {
> + buf += 6;
> + early_mmio_serial_init(buf);
> early_console_register(&early_serial_console, keep);
> - buf += 4;
> }
> if (!strncmp(buf, "serial", 6)) {
> buf += 6;
> --
> 2.47.2
>
