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From: "Maciej W. Rozycki" <macro@orcam.me.uk>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
	linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: [PATCH v5 1/5] serial: 8250: Also set sticky MCR bits in console restoration
Date: Mon, 18 Apr 2022 16:27:10 +0100 (BST)	[thread overview]
Message-ID: <alpine.DEB.2.21.2204181518490.9383@angie.orcam.me.uk> (raw)
In-Reply-To: <alpine.DEB.2.21.2204181506000.9383@angie.orcam.me.uk>

Sticky MCR bits are lost in console restoration if console suspending 
has been disabled.  This currently affects the AFE bit, which works in 
combination with RTS which we set, so we want to make sure the UART 
retains control of its FIFO where previously requested.  Also specific 
drivers may need other bits in the future.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Fixes: 4516d50aabed ("serial: 8250: Use canary to restart console after suspend")
Cc: stable@vger.kernel.org # v4.0+
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
Changes from v4:

- Reorder as 1/5 (from 4/5).

New change in v4, factored out from 5/5.
---
 drivers/tty/serial/8250/8250_port.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

linux-serial-8250-mcr-restore.diff
Index: linux-macro/drivers/tty/serial/8250/8250_port.c
===================================================================
--- linux-macro.orig/drivers/tty/serial/8250/8250_port.c
+++ linux-macro/drivers/tty/serial/8250/8250_port.c
@@ -3308,7 +3308,7 @@ static void serial8250_console_restore(s
 
 	serial8250_set_divisor(port, baud, quot, frac);
 	serial_port_out(port, UART_LCR, up->lcr);
-	serial8250_out_MCR(up, UART_MCR_DTR | UART_MCR_RTS);
+	serial8250_out_MCR(up, up->mcr | UART_MCR_DTR | UART_MCR_RTS);
 }
 
 /*

  reply	other threads:[~2022-04-18 15:47 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-18 15:27 [PATCH v5 0/5] serial: 8250: Fixes for Oxford Semiconductor 950 UARTs Maciej W. Rozycki
2022-04-18 15:27 ` Maciej W. Rozycki [this message]
2022-04-18 15:27 ` [PATCH v5 2/5] serial: 8250: Correct the clock for EndRun PTP/1588 PCIe device Maciej W. Rozycki
2022-04-18 15:27 ` [PATCH v5 3/5] serial: 8250: Fold EndRun device support into OxSemi Tornado code Maciej W. Rozycki
2022-04-18 15:27 ` [PATCH v5 4/5] serial: 8250: Export ICR access helpers for internal use Maciej W. Rozycki
2022-04-18 15:27 ` [PATCH v5 5/5] serial: 8250: Add proper clock handling for OxSemi PCIe devices Maciej W. Rozycki

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