linux-kernel - Re: [PATCH v1 3/5] tty: serial: meson: apply ttyS devname instead of ttyAML for new SoCs

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Message-ID: <20230704171326.tyforkt7z23zmgqa@CAB-WSD-L081021>
Date:   Tue, 4 Jul 2023 20:13:26 +0300
From:   Dmitry Rokosov <ddrokosov@...rdevices.ru>
To:     Conor Dooley <conor@...nel.org>
CC:     <gregkh@...uxfoundation.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <neil.armstrong@...aro.org>, <jbrunet@...libre.com>,
        <jirislaby@...nel.org>, <khilman@...libre.com>,
        <martin.blumenstingl@...glemail.com>, <kelvin.zhang@...ogic.com>,
        <xianwei.zhao@...ogic.com>, <kernel@...rdevices.ru>,
        <rockosov@...il.com>, <linux-amlogic@...ts.infradead.org>,
        <linux-serial@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v1 3/5] tty: serial: meson: apply ttyS devname instead of
 ttyAML for new SoCs

On Tue, Jul 04, 2023 at 05:57:15PM +0100, Conor Dooley wrote:
> On Tue, Jul 04, 2023 at 04:59:34PM +0300, Dmitry Rokosov wrote:
> > It is worth noting that the devname ttyS is a widely recognized tty name
> > and is commonly used by many uart device drivers. Given the established
> > usage and compatibility concerns, it may not be feasible to change the
> > devname for older SoCs. However, for new definitions, it is acceptable
> > and even recommended to use a new devname to help ensure clarity and
> > avoid any potential conflicts on lower or upper software levels.
> 
> > In
> > addition, modify the meson_uart_dt match data for g12a, a1, and s4 to
> > their appropriate values to ensure proper devname values and
> > functionality.
> 
> IMO, this is a separate change that should be in another patch, had to
> go looking through a several of unrelated $subject patches to understand
> how the binding patch was going to work.

I apologize, but I'm having difficulty understanding your suggestion.
Are you recommending that a distinct binding patch for meson-uart-a1 be
sent as part of a separate patch series? From my perspective, isolating
the binding patch may not provide all the necessary context as it is
reliant on a separate 'compatible' declaration within the meson-uart
driver. However, this declaration is interconnected with the devname
support patchset. Therefore, it seems that all of these patches are
linked together.

> > For more information please refer to IRC discussion at [1].
> > 
> > Links:
> >     [1]: https://libera.irclog.whitequark.org/linux-amlogic/2023-07-03
> > 
> > Signed-off-by: Dmitry Rokosov <ddrokosov@...rdevices.ru>
> > ---
> >  drivers/tty/serial/meson_uart.c | 33 +++++++++++++++++++++++++++++++--
> >  1 file changed, 31 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
> > index 87c0eb5f2dba..361f9326b527 100644
> > --- a/drivers/tty/serial/meson_uart.c
> > +++ b/drivers/tty/serial/meson_uart.c
> > @@ -82,6 +82,7 @@ static struct uart_driver meson_uart_driver;
> >  static struct uart_port *meson_ports[AML_UART_PORT_NUM];
> >  
> >  struct meson_uart_data {
> > +	const char *dev_name;
> >  	bool has_xtal_div2;
> >  };
> >  
> > @@ -683,6 +684,7 @@ static int meson_uart_probe_clocks(struct platform_device *pdev,
> >  
> >  static int meson_uart_probe(struct platform_device *pdev)
> >  {
> > +	const struct meson_uart_data *priv_data;
> >  	struct resource *res_mem;
> >  	struct uart_port *port;
> >  	u32 fifosize = 64; /* Default is 64, 128 for EE UART_0 */
> > @@ -729,6 +731,18 @@ static int meson_uart_probe(struct platform_device *pdev)
> >  	if (ret)
> >  		return ret;
> >  
> > +	priv_data = device_get_match_data(&pdev->dev);
> > +
> > +	if (priv_data) {
> > +		struct console *cons = meson_uart_driver.cons;
> > +
> > +		meson_uart_driver.dev_name = priv_data->dev_name;
> > +
> > +		if (cons)
> > +			strscpy(cons->name, priv_data->dev_name,
> > +				sizeof(cons->name));
> > +	}
> > +
> >  	if (!meson_uart_driver.state) {
> >  		ret = uart_register_driver(&meson_uart_driver);
> >  		if (ret)
> > @@ -748,7 +762,7 @@ static int meson_uart_probe(struct platform_device *pdev)
> >  	port->x_char = 0;
> >  	port->ops = &meson_uart_ops;
> >  	port->fifosize = fifosize;
> > -	port->private_data = (void *)device_get_match_data(&pdev->dev);
> > +	port->private_data = (void *)priv_data;
> >  
> >  	meson_ports[pdev->id] = port;
> >  	platform_set_drvdata(pdev, port);
> > @@ -780,6 +794,17 @@ static int meson_uart_remove(struct platform_device *pdev)
> >  }
> >  
> >  static struct meson_uart_data meson_g12a_uart_data = {
> > +	.dev_name = "ttyAML",
> > +	.has_xtal_div2 = true,
> > +};
> > +
> > +static struct meson_uart_data meson_a1_uart_data = {
> > +	.dev_name = "ttyS",
> > +	.has_xtal_div2 = false,
> > +};
> > +
> > +static struct meson_uart_data meson_s4_uart_data = {
> > +	.dev_name = "ttyS",
> >  	.has_xtal_div2 = true,
> >  };
> >  
> > @@ -794,7 +819,11 @@ static const struct of_device_id meson_uart_dt_match[] = {
> >  	},
> >  	{
> >  		.compatible = "amlogic,meson-s4-uart",
> > -		.data = (void *)&meson_g12a_uart_data,
> > +		.data = (void *)&meson_s4_uart_data,
> > +	},
> > +	{
> > +		.compatible = "amlogic,meson-a1-uart",
> > +		.data = (void *)&meson_a1_uart_data,
> >  	},
> >  	{ /* sentinel */ },
> >  };
> > -- 
> > 2.36.0
> > 



-- 
Thank you,
Dmitry