Hello Stephen,

On Mon, Jun 25, 2018 at 04:46:24PM -0700, Stephen Boyd wrote:

Quoting Matti Vaittinen (2018-06-13 06:03:38)

quoted

On Tue, Jun 12, 2018 at 11:23:54AM +0300, Matti Vaittinen wrote:

quoted

I see. This makes sense. I need to verify from HW colleagues whether
this chip has internal oscillator or not. I originally thought we have
on-chip oscillator - but as you say, we do have XIN pin in documentation.
So now I am not sure if the test board I have contains oscillator driving
the clk on PMIC - or if the PMIC has internal oscillator. I'll clarify this.

It really turned out that the PMIC just acts as a clock buffer. So I do
as you suggested and add lookup for parent clock to the driver. I
planned to do it so that if no parent is found from DT - then we assume
the 32.768KHz clock (as described in documentation). Eg, something along
the lines:

        init.parent_names = of_clk_get_parent_name(pdev->dev.parent->of_node, 0);
        if (init.parent_names) {
                init.num_parents = 1;
        } else {
                /* If parent is not given from DT we assume the typical use-case with
                 * 32.768 KHz oscillator for RTC (Maybe we could just error out here?)
                 */
                c->rate = BD71837_CLK_RATE;
                bd71837_clk_ops.recalc_rate = &bd71837_clk_recalc_rate;
        }

You can also add a clk directly in this driver in that case there isn't
one in DT with the rate and name of your choosing. Then the logic is the
same and we don't need a c->rate variable.

So you mean that I should use clk_hw_register_fixed_rate and create new
clk if parent is not found? Isn't this a bit of an overkill? Downside is
that then we do need remove/cleanup functionality for deleting this
parent clock - and I didn't find devm support for fixed clock. Furthermore
I guess that since it is parent, it can't be removed before child is removed.

Or did you mean something else but creating a fixed rate clock as parent
here?

Best Regards
    Matti Vaittinen