linux-kernel - [tip: x86/urgent] x86/early_printk: Use 'mmio32' for consistency, fix comments

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Message-ID: <174419906679.31282.16262283502465088009.tip-bot2@tip-bot2>
Date: Wed, 09 Apr 2025 11:44:26 -0000
From: "tip-bot2 for Andy Shevchenko" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 Ingo Molnar <mingo@...nel.org>, Denis Mukhin <dmukhin@...d.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/early_printk: Use 'mmio32' for consistency, fix
 comments

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     996457176bb7c64b3d30996592c754205ec4d3ea
Gitweb:        https://git.kernel.org/tip/996457176bb7c64b3d30996592c754205ec4d3ea
Author:        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
AuthorDate:    Mon, 07 Apr 2025 20:22:14 +03:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Wed, 09 Apr 2025 12:27:08 +02:00

x86/early_printk: Use 'mmio32' for consistency, fix comments

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.

Also, while at it, fix the comment for the "pciserial" case. The comment
seems to be a copy'n'paste error when mentioning "serial" instead of
"pciserial" (with double quotes). Fix this.

With that, move it upper, so we don't calculate 'buf' twice.

Fixes: 3181424aeac2 ("x86/early_printk: Add support for MMIO-based UARTs")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Denis Mukhin <dmukhin@...d.com>
Link: https://lore.kernel.org/r/20250407172214.792745-1-andriy.shevchenko@linux.intel.com
---
 Documentation/admin-guide/kernel-parameters.txt |  5 +----
 arch/x86/kernel/early_printk.c                  | 10 +++++-----
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 76e538c..d9fd26b 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 611f27e..3aad78b 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -389,10 +389,10 @@ 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;
@@ -407,9 +407,9 @@ static int __init setup_early_printk(char *buf)
 		}
 #ifdef CONFIG_PCI
 		if (!strncmp(buf, "pciserial", 9)) {
-			early_pci_serial_init(buf + 9);
+			buf += 9; /* Keep from match the above "pciserial" */
+			early_pci_serial_init(buf);
 			early_console_register(&early_serial_console, keep);
-			buf += 9; /* Keep from match the above "serial" */
 		}
 #endif
 		if (!strncmp(buf, "vga", 3) &&