linux-kernel - Re: [PATCH v4 3/3] serial: 8250_of: manage bus clock in suspend/resume

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Message-ID: <20250411220425-GYA22939@gentoo>
Date: Fri, 11 Apr 2025 22:04:25 +0000
From: Yixun Lan <dlan@...too.org>
To: Alex Elder <elder@...cstar.com>
Cc: gregkh@...uxfoundation.org, jirislaby@...nel.org, robh@...nel.org,
	krzk+dt@...nel.org, conor+dt@...nel.org, andy.shevchenko@...il.com,
	benjamin.larsson@...exis.eu, bastien.curutchet@...tlin.com,
	andriy.shevchenko@...ux.intel.com, u.kleine-koenig@...libre.com,
	lkundrak@...sk, devicetree@...r.kernel.org,
	linux-serial@...r.kernel.org, spacemit@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/3] serial: 8250_of: manage bus clock in
 suspend/resume

hi Alex,

Glad to see first 2 patches already accepted
This version is better than v3, thanks

On 15:38 Fri 11 Apr     , Alex Elder wrote:
> Save the bus clock pointer in the of_serial_info structure, and use
> that to disable the bus clock on suspend and re-enable it on resume.
> 
> Signed-off-by: Alex Elder <elder@...cstar.com>
Reviewed-by: Yixun Lan <dlan@...too.org>

> ---
>  drivers/tty/serial/8250/8250_of.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
> index a90a5462aa72a..d178b6c54ea18 100644
> --- a/drivers/tty/serial/8250/8250_of.c
> +++ b/drivers/tty/serial/8250/8250_of.c
> @@ -24,6 +24,7 @@
>  
>  struct of_serial_info {
>  	struct clk *clk;
> +	struct clk *bus_clk;
>  	struct reset_control *rst;
>  	int type;
>  	int line;
> @@ -138,6 +139,7 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
>  			goto err_pmruntime;
>  		}
>  
> +		info->bus_clk = bus_clk;
>  		port->uartclk = clk_get_rate(info->clk);
>  	}
>  	/* If current-speed was set, then try not to change it. */
> @@ -299,6 +301,7 @@ static int of_serial_suspend(struct device *dev)
>  	if (!uart_console(port) || console_suspend_enabled) {
>  		pm_runtime_put_sync(dev);
>  		clk_disable_unprepare(info->clk);
> +		clk_disable_unprepare(info->bus_clk);
>  	}
>  	return 0;
>  }
> @@ -311,6 +314,7 @@ static int of_serial_resume(struct device *dev)
>  
>  	if (!uart_console(port) || console_suspend_enabled) {
>  		pm_runtime_get_sync(dev);
> +		clk_prepare_enable(info->bus_clk);
>  		clk_prepare_enable(info->clk);
>  	}
>  
> -- 
> 2.45.2
> 
> 

-- 
Yixun Lan (dlan)
Gentoo Linux Developer
GPG Key ID AABEFD55