From: git@gregoirelayet.com
To: Tan Siewert <tan.siewert@9elements.com>,
Phil Rosenthal <phil@phil.gs>,
Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jirislaby@kernel.org>,
Corey Minyard <corey@minyard.net>,
"openipmi-developer@lists.sourceforge.net"
<openipmi-developer@lists.sourceforge.net>,
Andy Shevchenko <andy@kernel.org>, Joel Stanley <joel@jms.id.au>,
Andrew Jeffery <andrew@codeconstruct.com.au>,
Ryan Chen <ryan_chen@aspeedtech.com>,
"linux-aspeed@lists.ozlabs.org" <linux-aspeed@lists.ozlabs.org>,
Ninad Palsule <ninad@linux.ibm.com>, Andrew Lunn <andrew@lunn.ch>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>
Subject: Re: [PATCH] serial: 8250_pci: Add support for ASPEED BMC VUARTs over PCIe
Date: Mon, 12 Oct 2026 21:57:51 +0200 (CEST) [thread overview]
Message-ID: <1803265916.1474637.1791835071520@app.mailbox.org> (raw)
In-Reply-To: <e2e3d98b-9a89-4845-aa7d-0e23a1d95f70@9elements.com>
Hey !
> @Grégoire do you remember why `8250_aspeed_vuart` sets the PCIe class
> code to `0xff000000`?
The ASPEED chip can expose multiple things over the PCI bus (VUART, KCS, mailbox and shared memory). From my research, there is no such thing in the PCI specification for MFD PCIe class, or a way to specify multiple classes.
Also, assigning a PCI class as UART or IPMI KCS would cause some drivers to probe it automatically, binding the resource.
Even then, UART and IPMI KCS drivers assume specific offsets for the data paths which are incompatible with the ones from ASPEED.
Setting it to Unassigned class 0xFF seems to be a good fit.
I hope this clears things out.
Regards,
Grégoire
prev parent reply other threads:[~2026-10-12 19:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-08 13:27 Phil Rosenthal via B4 Relay
[not found] ` <sashiko-outbox-164226@kernel.org>
2026-10-08 17:38 ` Phil Rosenthal
2026-10-09 8:57 ` Andy Shevchenko
2026-10-09 13:45 ` Phil Rosenthal
2026-10-10 8:10 ` Andy Shevchenko
2026-10-10 10:47 ` Phil Rosenthal
2026-10-11 16:18 ` Tan Siewert
2026-10-11 17:00 ` Phil Rosenthal
2026-10-12 19:57 ` git [this message]
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