Re: [PATCH V3 3/4] 8250: 8250_f81504: Add Fintek F81504/508/512 PCIE-to-UART/GPIO UART support

[Peter Hung]

Hi Andy,

Andy Shevchenko æ 2016/2/16 äå 05:11 åé:
> On Tue, 2016-02-16 at 14:55 +0800, Peter Hung wrote:
> > +static u32 baudrate_table[] = { 1500000, 1152000, 921600 };
> > +static u8 clock_table[] = { F81504_CLKSEL_24_MHZ,
> > F81504_CLKSEL_18DOT46_MHZ,
> > +				F81504_CLKSEL_14DOT77_MHZ };
>
> I suggest to replace DOT by _.

ok

> > +/* We should do proper H/W transceiver setting before change to
> > RS485 mode */
> > +static int f81504_rs485_config(struct uart_port *port,
> > +			       struct serial_rs485 *rs485)
> > +{
> > +	u8 setting;
> > +	u8 *index = (u8 *) port->private_data;
>
> private_data is a type of void *, therefore no need to have an explicit
> casting.

ok


> > +static int f81504_check_baudrate(u32 baud, size_t *idx)
> > +{
> > +	size_t index;
> > +	u32 quot, rem;
> > +
> > +	for (index = 0; index < ARRAY_SIZE(baudrate_table); ++index)
>
> Post-increment is also okay.
>
> > {
> > +		/* Clock source must largeer than desire baudrate */
> > +		if (baud > baudrate_table[index])
> > +			continue;
> > +
> > +		quot = DIV_ROUND_CLOSEST(baudrate_table[index],
> > baud);
>
> So, how quot is used and is it possible to set, for example, baud rate
> as 1000000 or 576000?

The IC don't support B1000000 due to no 16MHz clock source.

The quot & rem is only use for compare, and it's must be not 0
when the code run to calculate DIV_ROUND_CLOSEST. So quot
is a redundancy here.

This function will find the suitable clock source for future use.
We'll pass suitable baud rate * 16 to port->uartclk for
serial8250_do_set_termios() to do advance divider operations.

I'll rewrite this section with remove quot and direct check
the "baudrate_table[index] % baud" divisible.


> > +	u8 tmp, *offset = (u8 *) port->private_data;
>
> Same for provate_data as above.

ok


> > +			/*
> > +			 * direct use 1.8432MHz when baudrate
> > smaller then or
> > +			 * equal 115200bps
>
> Check your style of comments in a _whole_ your series.

ok


> > +			/*
> > +			 * If it can't found suitable clock source
> > but had old
> > +			 * accpetable baudrate, we'll use it
>
> Typo: acceptable.
> Baudrate ->  baud rate.

ok

> > +	port.port.private_data = data;	/* save current idx */
>
> Not sure you need to allocate memory for that at all, or maybe use a
> struct with one member (for now).

We just pass the index of PCI configuration space currently. So
I just set a allocated u8 memory to private data. We'll maintain
current method.


> > +static SIMPLE_DEV_PM_OPS(f81504_serial_pm_ops,
> > f81504_serial_suspend,
> > +		f81504_serial_resume);
> > +
> > +static struct platform_driver f81504_serial_driver = {
> > +	.driver = {
> > +		.name	= F81504_SERIAL_NAME,
> > +		.owner	= THIS_MODULE,
>
> You perhaps don't need this. Check the rest of the modules.

ok


> > +config SERIAL_8250_F81504
> > +        tristate "Fintek F81504/508/512 16550 PCIE device support"
> > if EXPERT
> > +        depends on SERIAL_8250 && MFD_FINTEK_F81504_CORE
> > +        default SERIAL_8250
> > +        select RATIONAL
>
> It seems RATIONAL API is not used here.

This driver hadn't use RATIONAL API. I'll remove it.


Thanks for your advice.
--
With Best Regards,
Peter Hung