linux-kernel - Re: [PATCH v3 5/5] tty/serial: Add Spreadtrum sc9836-uart driver support

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Date:	Wed, 26 Nov 2014 12:33:13 +0000
From:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
To:	Chunyan Zhang <chunyan.zhang@...eadtrum.com>
Cc:	<grant.likely@...aro.org>, <robh+dt@...nel.org>,
	<catalin.marinas@....com>, <gregkh@...uxfoundation.org>,
	<ijc+devicetree@...lion.org.uk>, <jslaby@...e.cz>,
	<galak@...eaurora.org>, <broonie@...aro.org>,
	<mark.rutland@....com>, <m-karicheri2@...com>,
	<pawel.moll@....com>, <artagnon@...il.com>, <rrichter@...ium.com>,
	<will.deacon@....com>, <arnd@...db.de>, <corbet@....net>,
	<jason@...edaemon.net>, <broonie@...nel.org>, <heiko@...ech.de>,
	<shawn.guo@...escale.com>, <florian.vaussard@...l.ch>,
	<andrew@...n.ch>, <hytszk@...il.com>, <orsonzhai@...il.com>,
	<geng.ren@...eadtrum.com>, <zhizhou.zhang@...eadtrum.com>,
	<lanqing.liu@...eadtrum.com>, <zhang.lyra@...il.com>,
	<wei.qiao@...eadtrum.com>, <devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <sprdlinux@...elists.org>,
	<linux-doc@...r.kernel.org>, <linux-serial@...r.kernel.org>,
	<linux-api@...r.kernel.org>
Subject: Re: [PATCH v3 5/5] tty/serial: Add Spreadtrum sc9836-uart driver
 support

> +		 213 = /dev/ttySPX0		SPRD serial port 0
> +		    ...
> +		 216 = /dev/ttySPX3		SPRD serial port 3

Please use dynamic allocation or give a very very good reason why you
can't

> +config SERIAL_SPRD_NR
> +        int "Maximum number of sprd serial ports"
> +        depends on SERIAL_SPRD
> +        default "4"

If you are doing dynamic allocation this should pretty much go away


> +static int sprd_startup(struct uart_port *port)
> +{
> +	int ret = 0;
> +	unsigned int ien, ctrl1;
> +	struct sprd_uart_port *sp;
> +
> +	serial_out(port, SPRD_CTL2, ((THLD_TX_EMPTY << 8) | THLD_RX_FULL));
> +
> +	/* clear rx fifo */
> +	while (serial_in(port, SPRD_STS1) & 0x00ff)
> +		serial_in(port, SPRD_RXD);
> +
> +	/* clear tx fifo */
> +	while (serial_in(port, SPRD_STS1) & 0xff00)
> +		;

Missing a cpu_relax and I would have thought a timeout on both of these.


> +static void sprd_set_termios(struct uart_port *port,
> +				    struct ktermios *termios,
> +				    struct ktermios *old)
> +{
> +	unsigned int baud, quot;

> +	/* calculate parity */
> +	lcr &= ~SPRD_LCR_PARITY;
> +	if (termios->c_cflag & PARENB) {
> +		lcr |= SPRD_LCR_PARITY_EN;
> +		if (termios->c_cflag & PARODD)
> +			lcr |= SPRD_LCR_ODD_PAR;
> +		else
> +			lcr |= SPRD_LCR_EVEN_PAR;
> +	}

If you don't support mark/space parity then also clear CMSPAR in
termios->c_cflag. If you do then it ought to be handled above.

> +
> +	/* clock divider bit16~bit20 */
> +	serial_out(port, SPRD_CLKD1, (quot & 0x1f0000) >> 16);
> +	serial_out(port, SPRD_LCR, lcr);
> +	fc |= 0x3e00 | THLD_RX_FULL;
> +	serial_out(port, SPRD_CTL1, fc);

Also set the resulting baud back into the termios (see the 8250 termios
for an example)


> +static int __init sprd_console_setup(struct console *co, char *options)
> +{
> +	struct uart_port *port;
> +	int baud = 115200;
> +	int bits = 8;
> +	int parity = 'n';
> +	int flow = 'n';
> +
> +	if (unlikely(co->index >= UART_NR_MAX || co->index < 0))
> +		co->index = 0;
> +
> +	port = (struct uart_port *)sprd_port[co->index];
> +	if (port == NULL) {
> +		pr_info("srial port %d not yet initialized\n", co->index);

Typo

Looks basically sound to me

Alan
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