linux-kernel - R: R: [PATCH v1] serial: 8250_fintek: Print Fintek chip name

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Date:   Tue, 15 Dec 2020 14:06:09 +0000
From:   Flavio Suligoi <f.suligoi@...m.it>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     Jiri Slaby <jirislaby@...nel.org>,
        "Gustavo A . R . Silva" <gustavoars@...nel.org>,
        Ji-Ze Hong <hpeter@...il.com>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: R: R: [PATCH v1] serial: 8250_fintek: Print Fintek chip name

Hi Greg,


> > > > +		chip_name = "F81216H";
> > > > +		break;
> > > >  	case CHIP_ID_F81216:
> > > > +		chip_name = "F81216";
> > > >  		break;
> > > >  	default:
> > > >  		return -ENODEV;
> > > >  	}
> > > >
> > > >  	pdata->pid = chip;
> > > > +
> > > > +	pr_info("%s%s%s Fintek %s\n",
> > > > +		uart->port.dev ? dev_name(uart->port.dev) : "",
> > > > +		uart->port.dev ? ": " : "",
> > > > +		uart->port.name,
> > > > +		chip_name);
> > >
> > > Drivers, if all goes well, should not print anything to the kernel
> log.
> > > This isn't ok.
> > >
> > > And even if it was, dev_info() would be the correct thing to do...
> >
> > Ok, too many information in the driver.
> >
> > But what do you think about the possibility to introduce
> > a new additional field, in "serial8250_config" structure,
> > such as "extra_name" or something like this:
> >
> > struct serial8250_config {
> > 	const char		*name;
> > 	const char		*extra_name;
> > 	unsigned short	fifo_size;
> > 	unsigned short	tx_loadsz;
> > 	unsigned char	fcr;
> > 	unsigned char	rxtrig_bytes[UART_FCR_R_TRIG_MAX_STATE];
> > 	unsigned int	flags;
> > };
> >
> > In this way, if required, each driver can fill this
> > additional field, for example adding the name of
> > the particular uart chip or other useful info.
> >
> > As result, for example, the "uart_report_port" function output
> > could be something like this:
> >
> > 00:01: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A -
> Fintek F81216AD
> > 00:02: ttyS3 at I/O 0x2e8 (irq = 11, base_baud = 115200) is a 16550A -
> Fintek F81216AD
> >
> > where the "extra_name", if not empty, is printed
> > at the end of the line.
> > For practical space reasons, the "extra_name" length
> > can be limited to 16 chars.
> 
> Why?  What tool will use this, and why would userspace care about it?
> 
> What problem are you trying to solve here?

I try to explain my requirement:

we produce some x86 boards with multistandard RS232/422/485 ports
and, to have this feature, in some of these boards, we use a
Fintek uart or superIO.
So this additional info "extra_name" can be useful for
a quick check if the serial ports are multistandard or not,
without any other investigations, but using only a simple command
like:

dmesg| grep ttyS

> 
> thanks,
> 
> greg k-h

Thanks and best regards,
Flavio