Re: [PATCH 05/18] tty: serial: samsung_tty: add support for Apple UARTs

[Hector Martin]

On 08/02/2021 19.54, Krzysztof Kozlowski wrote:
> > +enum s3c24xx_irq_type {
> > +	IRQ_DISCRETE = 0,
> > +	IRQ_S3C6400 = 1,
> > +	IRQ_APPLE = 2,
>
> It seems you add the third structure to differentiate type of UART.
> There is already port type and s3c24xx_serial_drv_data, no need for
> third structure (kind of similar to tries of Tamseel Shams in recent
> patches). It's too much. Instead, differentiate by port type or prepare
> own set of uart_ops if it's really different (like you did with startup
> op).

This ties into little changes in a bunch of places, so separate uart_ops 
 callbacks for every one of those would end up duplicating a lot of code :(

That list is just used to map the port type to something that only 
represents the type of IRQs, but its only real purpose for the 
indirection is so I can do "== IRQ_DISCRETE" in some codepaths to mean 
"not apple or S3C6400".

e.g.

    if (s3c24xx_irq_type(port) == IRQ_DISCRETE)
        free_irq(ourport->rx_irq, ourport);

Would have to become

    if (port->type != IRQ_S3C6400 && port->type != IRQ_APPLE)
        free_irq(ourport->rx_irq, ourport);

or

    switch (port->type) {
    case IRQ_S3C6400:
    case IRQ_APPLE:
        break;
    default:
        free_irq(ourport->rx_irq, ourport);
    }

Which one do you prefer?

Aside: Marc didn't like introducing new port types into uapi, but if we 
don't do that then we need a "real" port type in drv_data that isn't the 
uapi-exposed port or something along those lines, with a separate enum 
containing all the true port type values for that.

> >   	/* Startup sequence is different for s3c64xx and higher SoC's */
> > -	if (s3c24xx_serial_has_interrupt_mask(port))
> > +	case IRQ_S3C6400:
> >   		s3c24xx_serial_ops.startup = s3c64xx_serial_startup;
>
> Don't overwrite specific ops. It's difficult to see then which ops are
> being used. Instead create a new set of uart_ops matching the needs.

s3c24xx_serial_ops was already doing that here, but I can move that to a 
a separate uart_ops too.

Ack on all the other comments, I'll make the changes for v2.

--
Hector Martin (marcan@xxxxxxxxx)
Public Key: https://mrcn.st/pub