Re: [PATCH v2 6/6] serial: 8250: make port operations work on struct uart_8250_port

On Tue, Oct 13, 2026 at 08:48:51AM +0200, Jiri Slaby (SUSE) wrote:

serial8250_register_8250_port() returns a line number and the other
port operations (serial8250_unregister_port(), serial8250_suspend_port(),
serial8250_resume_port()) accept it. Many drivers then convert the line
back to the port using serial8250_get_port() anyway.

Switch the interface to struct uart_8250_port:
* serial8250_register_8250_port() now returns the registered port, or
an ERR_PTR() on failure.
* serial8250_unregister_port(), serial8250_suspend_port() and
serial8250_resume_port() accept the port.

Convert all users accordingly. Drivers store the port pointer instead
of the line number. Several drivers kept a private struct only to hold
the line (airoha, dfl, em, fsl, ioc3); these are dropped and the port
is stored as drvdata directly.

This also fixes two latent issues:
* For a CIR port, serial8250_register_8250_port() used to return 0.
Callers stored this as the line, so a later unregister/suspend/resume
operated on ttyS0. Now the CIR port itself is returned.
* 8250_acorn checked ports[i] > 0 on removal, so a port registered as
line 0 was never unregistered.

There are no more users of serial8250_get_port() outside of the 8250
core, so drop its EXPORT.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>

Cc: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>

Why not having Ilpo's Cc in the below list?

Assisted-by: LLM
---
Cc: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@kernel.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Joel Stanley <joel@jms.id.au>
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Cc: Ryan Chen <ryan_chen@aspeedtech.com>
Cc: Billy Tsai <billy_tsai@aspeedtech.com>
Cc: Florian Fainelli <florian.fainelli@broadcom.com>
Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
Cc: Ray Jui <redacted>
Cc: Scott Branden <scott.branden@broadcom.com>
Cc: Al Cooper <alcooperx@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Paul Cercueil <paul@crapouillou.net>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Chaitanya Vadrevu <chaitanya.vadrevu@emerson.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Kumaravel Thiagarajan <kumaravel.thiagarajan@microchip.com>
Cc: Thierry Reding <thierry.reding@kernel.org>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Kees Cook <kees@kernel.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: "Uwe Kleine-König (The Capable Hub)" <redacted>
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Cc: linux-serial@vger.kernel.org
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Cc: linux-hardening@vger.kernel.org

[v2] include err.h (Ilpo)
---

...

 	seq_printf(s, "%7s: /dev/ptp%d\n", "PTP", ptp_clock_index(bp->ptp));
 	for (i = 0; i < __PORT_COUNT; i++) {

What about

		struct uart_8250_port *uport = bp->port[i].uport;

here and use it accordingly in the below code?

...

Since it takes a pointer now, make it error pointer and NULL-aware

	if (IS_ERR_OR_NULL(...))
		return;

there. With that being done, all this redundant NULL-checks will gone.

...

static void serial_card_remove(struct expansion_card *ec)

See my point?

...

static int aspeed_vuart_probe(struct platform_device *pdev)

You can get rid of these {} by using PTR_ERR_OR_ZERO(). Also do not define
variables in the middle of the code (it's only allowed for auto cleanup
variables and for-loop iterators).

...

I stopped here, I believe there are many similar cases which may be amended in
the same way as pointed out above.

-- 
With Best Regards,
Andy Shevchenko