On 04/08, Masahiro Yamada wrote:
This makes our driver programming life easier.
For example, let's see drivers/tty/serial/8250/8250_of.c
The "clock-frequency" DT property takes precedence over "clocks" property.
So, it is valid to probe the driver with a NULL pointer for info->clk.
if (of_property_read_u32(np, "clock-frequency", &clk)) {
/* Get clk rate through clk driver if present */
info->clk = devm_clk_get(&ofdev->dev, NULL);
if (IS_ERR(info->clk)) {
dev_warn(&ofdev->dev,
"clk or clock-frequency not defined\n");
return PTR_ERR(info->clk);
}
ret = clk_prepare_enable(info->clk);
if (ret < 0)
return ret;
clk = clk_get_rate(info->clk);
}
As a result, we need to make sure the clk pointer is valid
before calling clk_disable_unprepare().
If we could support pointer checking in callees, we would be able to
clean-up lots of clock consumers.
I'm not sure if you meant to use that example for the error
pointer case? It bails out if clk_get() returns an error pointer.
I'm all for a no-op in clk_disable()/unprepare() when the pointer
is NULL. But when it's an error pointer the driver should be
handling it and bail out before it would ever call enable/prepare
on it or disable/unprepare.
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