From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 773DC474258; Mon, 31 Aug 2026 13:35:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788183333; cv=none; b=tdtpHm8Y/F/K7WbLZn+FHWA0mn42k6Eo2Sx75o+HU7r4mibGfOFbBCmElkolcMizTt+xYXmp4/byI6V+LVK5AuMne3smwEV87IeNs1r/CndDEb0+TupQhF8I1Cu7lQFMuZ9n1QgW5O0w4HSwRXoBmj0Ovk7Mv8LtL7sIQ+2nzXI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788183333; c=relaxed/simple; bh=iT40572/qdpEhje0zAkqZD+F85USE+76aUbxnKzlqBM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=CPejS1DM+4erXxKE7QEY2LuDUYWKSSOGPhPLYpy1nf09FcLtM7VNF/RApBmxs4jNsSVe853dtMkTYA0Dsuey+TMi3Jip3jweczd7EYpY50r3xAPW/tPmaSFRAOphpf23gSmgVtiA3B3d6HcWUL+rW1gppDPPdGvwc4As5Q05Yo0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fmWToojn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fmWToojn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B6241F00A3F; Mon, 31 Aug 2026 13:35:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788183332; bh=KNrFfeYDmwUesWMPsLDUAa4EhpDeyOxaMh0XZ0qkKDo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fmWToojnb0vFwNFbXjvXaEAvAz98C+9Xb459IMMN3DToOk3+wIP6x5E2X4sL/TFKI EqVdeMm4vsGxls/vTMlIy9XVPDMVCswLLq4RGxE/ZxQIIkwaYvIs4zeBDPR3zTamDo W9QRnjWwaVA/CYBWReZXjkpuGooCVfSMguRWqR31zmzHD+Bi4D2AD5KOWVCs3fZQ6i lyM/lh3kX6GQ3i1lm6MATzJ14Isdu87I0BQ1ziJsGFPWcw1WUUmcwmYUyQS6kzyg+R EiK3tmUVUXfLiab9FVVFTBJqKZtaV6TO+ESQ9bpR/OzEEFAQfazukJ76DriKdWo0JR QmHVWN7Ih3pgQ== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Manuel Lauss , Greg Kroah-Hartman , Sasha Levin , jirislaby@kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Subject: [PATCH AUTOSEL 6.18] serial: 8250_port: recognize UPIO_AU Date: Mon, 31 Aug 2026 09:21:53 -0400 Message-ID: <20260831133314.4125787-85-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260831133314.4125787-1-sashal@kernel.org> References: <20260831133314.4125787-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.18.48 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Manuel Lauss [ Upstream commit 49fa670efdfdd27e29145cbd2beef065c08717ef ] My MIPS Alchemy systems generate the following warning during probe of the 8250 driver: WARNING: drivers/tty/serial/8250/8250_port.c:462 at set_io_from_upio+0xfc/0x124, CPU#0: swapper/0/1 Unsupported UART type 4 [...] [<80521d40>] set_io_from_upio+0xfc/0x124 [<80521dfc>] serial8250_set_defaults+0x94/0xe0 [<80520fb4>] serial8250_register_8250_port+0x288/0x51c [<805214ec>] serial8250_probe+0x160/0x1e8 [<8053b5f0>] platform_probe+0x64/0x90 The least invasive fix is to recognize UPIO_AU (type 4) in set_io_from_upio() and do nothing, since all parameters have already been set up in 8250_rt288x.c::au_platform_setup(). Run-tested on Alchemy Au1300 platform. Signed-off-by: Manuel Lauss Link: https://patch.msgid.link/20260430135822.905035-1-manuel.lauss@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- LLM Generated explanations, may be completely bogus: The background `git log -S "set_io_from_upio"` search finished. It points to `2bf95a9bcb500` ("serial: 8250: Fix 8250_rsa symbol loop") as the first non-merge change touching that symbol in this tree's history — consistent with the 6.18-era 8250 refactor that left `UPIO_AU` unhandled in `set_io_from_upio()`. That doesn't change the earlier conclusion for **v6.18.43**: backport **YES** — small, correct fix for a real boot-time WARN on MIPS Alchemy / RT288x UARTs where platform code already sets up the accessors. drivers/tty/serial/8250/8250_port.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 0c633639f7657..7c10087458bb6 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -458,6 +458,8 @@ static void set_io_from_upio(struct uart_port *p) p->serial_out = io_serial_out; break; #endif + case UPIO_AU: + break; default: WARN(p->iotype != UPIO_PORT || p->iobase, "Unsupported UART type %x\n", p->iotype); -- 2.53.0