On Fri, Jun 19, 2020 at 11:02:50PM +0300, Serge Semin wrote:
> Really instead of twice checking the clk_round_rate() return value
> we could do it once, and if it isn't error the clock rate can be changed.
> By doing so we decrease a number of ret-value tests and remove a weird
> goto-based construction implemented in the dw8250_set_termios() method.
This doesn't look right to me - neither the before code nor the after
code.
> clk_disable_unprepare(d->clk);
> rate = clk_round_rate(d->clk, baud * 16);
> - if (rate < 0)
> - ret = rate;
> - else if (rate == 0)
> - ret = -ENOENT;
> - else
> + if (rate > 0) {
> ret = clk_set_rate(d->clk, rate);
> + if (!ret)
> + p->uartclk = rate;
> + }
> clk_prepare_enable(d->clk);
>
> - if (ret)
> - goto out;
> -
> - p->uartclk = rate;
newrate = baud * 16;
clk_disable_unprepare(d->clk);
rate = clk_round_rate(newrate);
ret = clk_set_rate(d->clk, newrate);
if (!ret)
p->uartclk = rate;
ret = elk_prepare_enable(d->clk);
/* check ret for failure, means the clock is no longer running */
is all that should be necessary: note that clk_round_rate() is required
to return the rate that a successful call to clk_set_rate() would result
in for that clock. It is equivalent to:
ret = clk_set_rate(d->clk, newrate);
if (ret == 0)
p->uartclk = clk_get_rate(d->clk);
The other commonly misunderstood thing about the clk API is that the
rate you pass in to clk_round_rate() to discover the actual clock rate
and the value passed in to clk_set_rate() _should_ be the same value.
You should _not_ do clk_set_rate(clk, clk_round_rate(clk, newrate));
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