linux-kernel - Re: [linux-sunxi] [PATCH v4 2/6] clk: sunxi: Add H3 clocks support

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Date:	Thu, 5 Nov 2015 09:17:48 +1100
From:	Julian Calaby <julian.calaby@...il.com>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:	Jens Kuske <jenskuske@...il.com>, Chen-Yu Tsai <wens@...e.org>,
	Michael Turquette <mturquette@...libre.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Emilio López <emilio@...pez.com.ar>,
	Vishnu Patekar <vishnupatekar0510@...il.com>,
	Hans de Goede <hdegoede@...hat.com>,
	devicetree <devicetree@...r.kernel.org>,
	"Mailing List, Arm" <linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [linux-sunxi] [PATCH v4 2/6] clk: sunxi: Add H3 clocks support

Hi Maxime,

On Thu, Nov 5, 2015 at 3:23 AM, Maxime Ripard
<maxime.ripard@...e-electrons.com> wrote:
> Hi Julian,
>
> On Wed, Oct 28, 2015 at 10:12:09AM +1100, Julian Calaby wrote:
>> > +       of_property_for_each_u32(node, "clock-indices", prop, p, index) {
>> > +               of_property_read_string_index(node, "clock-output-names",
>> > +                                             i, &clk_name);
>> > +
>> > +               if (index == 17 || (index >= 29 && index <= 31))
>> > +                       clk_parent = AHB2;
>> > +               else if (index <= 63 || index >= 128)
>> > +                       clk_parent = AHB1;
>> > +               else if (index >= 64 && index <= 95)
>> > +                       clk_parent = APB1;
>> > +               else if (index >= 96 && index <= 127)
>> > +                       clk_parent = APB2;
>>
>> A way to make this reusable in the future might be to encode it in a
>> structure like:
>>
>> static const struct bus_clock_paths sun8i_h3_bus_clock_paths __initdata = {
>>         {.parent = 2, .min = 17, .max = 17}, /* index 17 is from AHB2 */
>>         {.parent = 2, .min = 29, .max = 31}, /* AHB2 bank */
>>         {.parent = 1, .min = 63, .max = 128}, /* AHB1 bank */
>> ...
>>         {}
>> };
>>
>> Then the code here can be reused for other clocks like this in the
>> future without too much bloat. (And this would potentially could be
>> generic enough for other platforms.)
>
> We don't really need that at the moment. There's not point in writing
> more complicated code to support a use case we don't have yet.
>
> (However, something along these lines will definitely be needed if we
> ever have another SoC having the same bus gates madness)

This was a suggestion for the future to address Jens' comment about
having a bus clock driver instead of encoding it in devicetree.

Thanks,

-- 
Julian Calaby

Email: julian.calaby@...il.com
Profile: http://www.google.com/profiles/julian.calaby/
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