Re: [PATCH v7 4/4] tty: serial: 8250: add DFL bus driver for Altera 16550.

From: Andy Shevchenko
Date: Tue Dec 20 2022 - 12:15:07 EST


On Tue, Dec 20, 2022 at 08:36:52AM -0800, matthew.gerlach@xxxxxxxxxxxxxxx wrote:
> From: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
>
> Add a Device Feature List (DFL) bus driver for the Altera
> 16550 implementation of UART.

In general the code here looks good to me, but one thing to discuss due to
comment to the previous patch(es).

...

> + u64 *p;
> +
> + p = dfh_find_param(dfl_dev, DFHv1_PARAM_ID_CLK_FRQ);
> + if (!p)
> + return dev_err_probe(dev, -EINVAL, "missing CLK_FRQ param\n");
> +
> + p++;
> + uart->port.uartclk = *p;

So, here and the below is using always the second u64 from the returned data.
Does it mean:
- we always skip the first u64 from the returned buffer and hence... (see below)
- we may actually return the second u64 as a plain number (not a pointer) from
(an additional?) API? In such case we would not need to take care about this
p++; lines here and there.
- we have fixed length of the data, returned by find_param(), i.e. 2 u64 words?

--
With Best Regards,
Andy Shevchenko