Re: [PATCH 1/6] clk: sunxi: Add support for sun9i a80 usb clocks and resets

Maxime Ripard
2014-11-05T10:11:05Z

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On Wed, Nov 05, 2014 at 06:02:35PM +0800, Chen-Yu Tsai wrote:
> >> +static void __init sunxi_usb_clk_setup(struct device_node *node,
> >> + const struct usb_clk_data *data,
> >> + spinlock_t *lock)
> >> +{
> >> + struct clk_onecell_data *clk_data;
> >> + struct usb_reset_data *reset_data;
> >> + const char *clk_parent;
> >> + const char *clk_name;
> >> + void __iomem *reg;
> >> + int qty;
> >> + int i = 0;
> >> + int j = 0;
> >> +
> >> + reg = of_iomap(node, 0);
> >
> > of_io_request_and_map?
>
> OK. About that, any recommended naming style for the 3rd argument?
> Maybe the driver name "clk_sun9i_usb"? Or just a generic name like
> "usb_clk"?
>
> I'm asking now as we'll likely be changing the existing drivers to
> use it as well.

I don't really have a preference. Maybe the DT node name would be both
the easier and better solution.

[...]

> >> +static void __init sun9i_a80_usb_mod_setup(struct device_node *node)
> >> +{
> >> + /* AHB1 gate must be enabled to access registers */
> >> + struct clk *ahb = of_clk_get(node, 0);
> >> +
> >> + WARN_ON(IS_ERR(ahb));
> >> + clk_prepare_enable(ahb);
> >
> > Hmmmm. That look off.
> >
> > Why do you need the clock to be enabled all the time? Isn't the CCF
> > already taking care of enabling the parent clock whenever it needs to
> > access any register?
>
> There are also resets in the same block. That and I couldn't get it
> working without enabling the clock beforehand.

Ah, right.

What happens if you just enable and disable the clocks in the
reset_assert and reset_deassert right before and after accessing the
registers?

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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