FAILED: patch "[PATCH] serial: sc16is7xx: fix broken port 0 uart init" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x 2861ed4d6e6d1a2c9de9bf5b0abd996c2dc673d0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023090345-unlimited-used-dc3f@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2861ed4d6e6d1a2c9de9bf5b0abd996c2dc673d0 Mon Sep 17 00:00:00 2001
From: Hugo Villeneuve <[email protected]>
Date: Mon, 7 Aug 2023 17:45:51 -0400
Subject: [PATCH] serial: sc16is7xx: fix broken port 0 uart init
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Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The sc16is7xx_config_rs485() function is called only for the second port (index 1, channel B), causing initialization problems for the first port.

For the sc16is7xx driver, port->membase and port->mapbase are not set, and their default values are 0. And we set port->iobase to the device index. This means that when the first device is registered using the uart_add_one_port() function, the following values will be in the port structure:

    port->membase = 0
    port->mapbase = 0
    port->iobase  = 0

Therefore, the function uart_configure_port() in serial_core.c will exit early because of the following check:

	/*
	 * If there isn't a port here, don't do anything further.
	 */
	if (!port->iobase && !port->mapbase && !port->membase)
		return;

Typically, I2C and SPI drivers do not set port->membase and port->mapbase.

The max310x driver sets port->membase to ~0 (all ones). By implementing the same change in this driver, uart_configure_port() is now correctly executed for all ports.

index 18a48ce052c2..ffe817309413 100644
@@ -1438,6 +1438,12 @@ static int sc16is7xx_probe(struct device *dev,
 		s->p[i].port.fifosize	= SC16IS7XX_FIFO_SIZE;
 		s->p[i].port.flags	= UPF_FIXED_TYPE | UPF_LOW_LATENCY;
 		s->p[i].port.iobase	= i;
+		/*
+		 * Use all ones as membase to make sure uart_configure_port() in
+		 * serial_core.c does not abort for SPI/I2C devices where the
+		 * membase address is not applicable.
+		 */
+		s->p[i].port.membase	= (void __iomem *)~0;
 		s->p[i].port.iotype	= UPIO_PORT;
 		s->p[i].port.uartclk	= freq;
 		s->p[i].port.rs485_config = sc16is7xx_config_rs485;