Commit 93810191 authored by Tony Lindgren's avatar Tony Lindgren Committed by Greg Kroah-Hartman
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serial: 8250: omap: Fix missing PM runtime calls for omap8250_set_mctrl() 



There are cases where omap8250_set_mctrl() may get called after the
UART has already autoidled causing an asynchronous external abort.

This can happen on ttyport_open():

mem_serial_in from omap8250_set_mctrl+0x38/0xa0
omap8250_set_mctrl from uart_update_mctrl+0x4c/0x58
uart_update_mctrl from uart_dtr_rts+0x60/0xa8
uart_dtr_rts from tty_port_block_til_ready+0xd0/0x2a8
tty_port_block_til_ready from uart_open+0x14/0x1c
uart_open from ttyport_open+0x64/0x148

And on ttyport_close():

omap8250_set_mctrl from uart_update_mctrl+0x3c/0x48
uart_update_mctrl from uart_dtr_rts+0x54/0x9c
uart_dtr_rts from tty_port_shutdown+0x78/0x9c
tty_port_shutdown from tty_port_close+0x3c/0x74
tty_port_close from ttyport_close+0x40/0x58

It can also happen on disassociate_ctty() calling uart_shutdown()
that ends up calling omap8250_set_mctrl().

Let's fix the issue by adding missing PM runtime calls to
omap8250_set_mctrl(). To do this, we need to add __omap8250_set_mctrl()
that can be called from both omap8250_set_mctrl(), and from runtime PM
resume path when restoring the registers.

Fixes: 61929cf0 ("tty: serial: Add 8250-core based omap driver")
Reported-by: default avatarMerlijn Wajer <merlijn@wizzup.org>
Reported-by: default avatarRomain Naour <romain.naour@smile.fr>
Reported-by: default avatarIvaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Tested-by: default avatarIvaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
Depends-on: dd8088d5 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
Link: https://lore.kernel.org/r/20221024063613.25943-1-tony@atomide.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 038ee49f

drivers/tty/serial/8250/8250_omap.c

+20 −2
Original line number Diff line number Diff line
@@ -157,7 +157,11 @@ static u32 uart_read(struct uart_8250_port *up, u32 reg) 
	return readl(up->port.membase + (reg << up->port.regshift));

}



static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl)

/*

 * Called on runtime PM resume path from omap8250_restore_regs(), and

 * omap8250_set_mctrl().

 */

static void __omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl)

{

	struct uart_8250_port *up = up_to_u8250p(port);

	struct omap8250_priv *priv = up->port.private_data;
@@ -181,6 +185,20 @@ static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl) 
	}

}



static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl)

{

	int err;



	err = pm_runtime_resume_and_get(port->dev);

	if (err)

		return;



	__omap8250_set_mctrl(port, mctrl);



	pm_runtime_mark_last_busy(port->dev);

	pm_runtime_put_autosuspend(port->dev);

}



/*

 * Work Around for Errata i202 (2430, 3430, 3630, 4430 and 4460)

 * The access to uart register after MDR1 Access
@@ -343,7 +361,7 @@ static void omap8250_restore_regs(struct uart_8250_port *up) 


	omap8250_update_mdr1(up, priv);



	up->port.ops->set_mctrl(&up->port, up->port.mctrl);

	__omap8250_set_mctrl(&up->port, up->port.mctrl);



	if (up->port.rs485.flags & SER_RS485_ENABLED)

		serial8250_em485_stop_tx(up);