linux-kernel - Re: [PATCH v9 02/10] serial: sc16is7xx: mark IOCONTROL register as volatile

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Message-ID: <2023073108-footboard-chooser-d20e@gregkh>
Date:   Mon, 31 Jul 2023 17:50:40 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Hugo Villeneuve <hugo@...ovil.com>
Cc:     robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        conor+dt@...nel.org, jirislaby@...nel.org, jringle@...dpoint.com,
        isaac.true@...onical.com, jesse.sung@...onical.com,
        l.perczak@...lintechnologies.com, tomasz.mon@...lingroup.com,
        linux-serial@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        Hugo Villeneuve <hvilleneuve@...onoff.com>,
        stable@...r.kernel.org, Lech Perczak <lech.perczak@...lingroup.com>
Subject: Re: [PATCH v9 02/10] serial: sc16is7xx: mark IOCONTROL register as
 volatile

On Tue, Jul 25, 2023 at 10:23:34AM -0400, Hugo Villeneuve wrote:
> 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

Why 6.1.y?  What commit does this fix?

> 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 8ae2afc76a9b..306ae512b38a 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;

Is this the same as this change:
	https://lore.kernel.org/all/20230724034727.17335-1-hui.wang@canonical.com/

confused,

greg k-h