linux-kernel - [PATCH v6 2/9] serial: sc16is7xx: mark IOCONTROL register as volatile

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Date:   Thu,  1 Jun 2023 16:18:37 -0400
From:   Hugo Villeneuve <hugo@...ovil.com>
To:     gregkh@...uxfoundation.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        jirislaby@...nel.org, jringle@...dpoint.com,
        tomasz.mon@...lingroup.com, l.perczak@...lintechnologies.com
Cc:     linux-serial@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, hugo@...ovil.com,
        linux-gpio@...r.kernel.org,
        Hugo Villeneuve <hvilleneuve@...onoff.com>,
        stable@...r.kernel.org, Lech Perczak <lech.perczak@...lingroup.com>
Subject: [PATCH v6 2/9] serial: sc16is7xx: mark IOCONTROL register as volatile

From: Hugo Villeneuve <hvilleneuve@...onoff.com>

Bit SRESET (3) is cleared when a reset operation is completed. Having
the IOCONTROL register as non-volatile will always read SRESET as 1,
which is incorrect.

Also, if IOCONTROL register is not a volatile register, the upcoming
patch "serial: sc16is7xx: fix regression with GPIO configuration"
doesn't work when setting some shared GPIO lines as modem control
lines.

Therefore mark IOCONTROL register as a volatile register.

Cc: <stable@...r.kernel.org> # 6.1.x
Signed-off-by: Hugo Villeneuve <hvilleneuve@...onoff.com>
Reviewed-by: Lech Perczak <lech.perczak@...lingroup.com>
Tested-by: Lech Perczak <lech.perczak@...lingroup.com>
---
 drivers/tty/serial/sc16is7xx.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index faa51a58671f..0c903d44429c 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -488,6 +488,7 @@ static bool sc16is7xx_regmap_volatile(struct device *dev, unsigned int reg)
 	case SC16IS7XX_TXLVL_REG:
 	case SC16IS7XX_RXLVL_REG:
 	case SC16IS7XX_IOSTATE_REG:
+	case SC16IS7XX_IOCONTROL_REG:
 		return true;
 	default:
 		break;
-- 
2.30.2