linux-kernel - Re: [PATCH v2 1/2] tty: serial: 8250

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Message-ID: <bf054186-17fb-4ea4-9d07-488b6792a437@collabora.com>
Date: Mon, 15 Sep 2025 15:41:25 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Daniel Golle <daniel@...rotopia.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Jiri Slaby <jirislaby@...nel.org>, Matthias Brugger
 <matthias.bgg@...il.com>, Uwe Kleine-König
 <u.kleine-koenig@...libre.com>, Yu Jiaoliang <yujiaoliang@...o.com>,
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 Changqi Hu <changqi.hu@...iatek.com>, Sam Shih <sam.shih@...iatek.com>,
 Steven Liu <steven.liu@...iatek.com>, John Crispin <john@...ozen.org>,
 linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v2 1/2] tty: serial: 8250_mtk: enable baud clock

Il 15/09/25 15:06, Daniel Golle ha scritto:
> Some MediaTek SoCs got a gated UART baud clock, which currently gets
> disabled as the clk subsystem believes it would be unused. This results in
> the uart freezing right after "clk: Disabling unused clocks" on those
> platforms.
> 
> To fix this request the baud clock to be prepared and enabled during probe.
> 
> Fixes: e32a83c70cf9 ("serial: 8250-mtk: modify mtk uart power and clock management")
> Suggested-by: Sam Shih <sam.shih@...iatek.com>
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>

Thanks for caring about power management. However, this and the addition in PM ops
should be a single commit. It's even using the same Fixes tag...! :-)

I've read both of the commits in this series and the code LGTM.


tty: serial: 8250_mtk: Enable baud clock and manage in runtime PM

Please, squash the two commits, after which...

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

Cheers,
Angelo

> ---
> v2: no changes
> 
>   drivers/tty/serial/8250/8250_mtk.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> index b44de2ed7413..9329ed1f759d 100644
> --- a/drivers/tty/serial/8250/8250_mtk.c
> +++ b/drivers/tty/serial/8250/8250_mtk.c
> @@ -475,13 +475,13 @@ static int mtk8250_probe_of(struct platform_device *pdev, struct uart_port *p,
>   	int dmacnt;
>   #endif
>   
> -	data->uart_clk = devm_clk_get(&pdev->dev, "baud");
> +	data->uart_clk = devm_clk_get_enabled(&pdev->dev, "baud");
>   	if (IS_ERR(data->uart_clk)) {
>   		/*
>   		 * For compatibility with older device trees try unnamed
>   		 * clk when no baud clk can be found.
>   		 */
> -		data->uart_clk = devm_clk_get(&pdev->dev, NULL);
> +		data->uart_clk = devm_clk_get_enabled(&pdev->dev, NULL);
>   		if (IS_ERR(data->uart_clk)) {
>   			dev_warn(&pdev->dev, "Can't get uart clock\n");
>   			return PTR_ERR(data->uart_clk);