linux-kernel - [PATCH] MIPS: rb532: Fix MMIO UART resource registration

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Message-Id: <20260205-rb532-uart-v1-1-334dbdfafa60@flygoat.com>
Date: Thu, 05 Feb 2026 10:08:42 +0000
From: Jiaxun Yang <jiaxun.yang@...goat.com>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
 Yi Yang <yiyang13@...wei.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org, 
 stable@...r.kernel.org, Waldemar Brodkorb <wbx@...nadk.org>, 
 Jiaxun Yang <jiaxun.yang@...goat.com>
Subject: [PATCH] MIPS: rb532: Fix MMIO UART resource registration

Since commit 6e690d54cfa8 ("serial: 8250: fix return error code in
serial8250_request_std_resource()"), registering an 8250 MMIO port
without mapbase no longer works, as the resource range is derived from
mapbase/mapsize.

Populate mapbase and mapsize accordingly. Also drop ugly membase KSEG1
pointer and set UPF_IOREMAP instead, letting the 8250 core perform the
ioremap.

Fixes: 6e690d54cfa8 ("serial: 8250: fix return error code in serial8250_request_std_resource()")
Cc: stable@...r.kernel.org
Reported-by: Waldemar Brodkorb <wbx@...nadk.org>
Link: https://lore.kernel.org/linux-mips/aX-d0ShTplHKZT33@waldemar-brodkorb.de/
Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
---
Since it's a partial fix to the issue report, I'll not use Closes
tag. checkpatch is unhappy :-(
---
 arch/mips/rb532/devices.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/mips/rb532/devices.c b/arch/mips/rb532/devices.c
index 8ecb56be81acc36e39192dee9f5d2a4d19b3755c..4f027efbf27b05377ddac306ff16714b8764915b 100644
--- a/arch/mips/rb532/devices.c
+++ b/arch/mips/rb532/devices.c
@@ -213,11 +213,12 @@ static struct platform_device rb532_wdt = {
 static struct plat_serial8250_port rb532_uart_res[] = {
 	{
 		.type           = PORT_16550A,
-		.membase	= (char *)KSEG1ADDR(REGBASE + UART0BASE),
+		.mapbase        = REGBASE + UART0BASE,
+		.mapsize        = 0x1000,
 		.irq		= UART0_IRQ,
 		.regshift	= 2,
 		.iotype		= UPIO_MEM,
-		.flags		= UPF_BOOT_AUTOCONF,
+		.flags		= UPF_BOOT_AUTOCONF | UPF_IOREMAP,
 	},
 	{
 		.flags		= 0,

---
base-commit: 0f8a890c4524d6e4013ff225e70de2aed7e6d726
change-id: 20260205-rb532-uart-5f2d2ff28eb8

Best regards,
-- 
Jiaxun Yang <jiaxun.yang@...goat.com>