linux-kernel - Re: [PATCH v7 2/2] serial:sunplus-uart:Add Sunplus SoC UART Driver

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Date:   Tue, 8 Feb 2022 07:27:04 +0100
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Hammer Hsieh <hammerh0314@...il.com>, gregkh@...uxfoundation.org,
        robh+dt@...nel.org, linux-serial@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        p.zabel@...gutronix.de
Cc:     wells.lu@...plus.com, hammer.hsieh@...plus.com
Subject: Re: [PATCH v7 2/2] serial:sunplus-uart:Add Sunplus SoC UART Driver

Hi,

On 07. 02. 22, 6:58, Hammer Hsieh wrote:
> +static void sunplus_shutdown(struct uart_port *port)
> +{
> +	unsigned long flags;
> +	unsigned int isc;
> +
> +	spin_lock_irqsave(&port->lock, flags);
> +
> +	isc = readl(port->membase + SUP_UART_ISC);
> +	isc &= ~(SUP_UART_ISC_RXM | SUP_UART_ISC_TXM);

Is this correct? I mean: will the SUP_UART_ISC read contain the control 
bits, not only status bits?

> +	writel(isc, port->membase + SUP_UART_ISC);
> +
> +	spin_unlock_irqrestore(&port->lock, flags);
> +
> +	free_irq(port->irq, port);

I am still waiting for explanation why this is safe with respect to 
posted writes.

regards,
-- 
js
suse labs