From: emilio@elopez•com.ar (Emilio López)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 4/9] clk: sunxi: PLL2 support for sun4i, sun5i and sun7i
Date: Mon, 04 Aug 2014 17:23:44 -0300 [thread overview]
Message-ID: <53DFEBD0.4050704@elopez.com.ar> (raw)
In-Reply-To: <20140804200200.GK3952@lukather>
El 04/08/14 a las 17:02, Maxime Ripard escibi?:
> On Sun, Aug 03, 2014 at 07:02:41PM -0300, Emilio L?pez wrote:
>> Hi,
>>
>> El 03/08/14 a las 09:44, Maxime Ripard escibi?:
>>> On Thu, Jul 31, 2014 at 06:28:07PM -0300, Emilio L?pez wrote:
>>>> This patch adds support for PLL2 and derivates on sun4i, sun5i and
>>>> sun7i SoCs. As this PLL is only used for audio and requires good
>>>> accuracy, we only support two known good rates.
>>>>
>>>> Signed-off-by: Emilio L?pez <emilio@elopez•com.ar>
>>>> ---
>>>>
>> (...)
>>>> + /* PLL2x8, double of PLL2 without the post divisor */
>>>> + of_property_read_string_index(np, "clock-output-names", 3, &clk_name);
>>>> + clks[3] = clk_register_fixed_factor(NULL, clk_name, parent,
>>>> + CLK_SET_RATE_PARENT, 2 * 4, 1);
>>>
>>> Why have you declared them here, instead of using fixed factors in the
>>> DT directly, like we have done in the past?
>>
>> I'd prefer to see one clock with four outputs represented as one
>> clock with four outputs rather than one clock with one output and
>> other three weirdly named nodes floating around.
>
> Except that you have no control over these 3 other outputs, that
> directly derive from the only one you can control.
You do have one degree of control, see below.
> Plus, their name wouldn't be weirded than the one you gave in
> clock-output-names ;)
Allwinner chose those names on the user manual, not me :)
>> I can only see four uses of fixed-factor-clock in our DTSI, three of
>> which are "pass through" clocks for ahb and ar100 on sun6/8i, and a
>> fourth one to implement the 32k that results from reducing the 24M
>> osc on sun7i.
>
> And PLLx2, PLL2x4, PLL2x8 are really just pass-through clocks
> too. Once PLL2 is controlled, those will just be enabled.
Yes and no.
>> As a second reason, implementing it as fixed factors would be
>> slightly incorrect, as it's only "x8" when you use the limited set
>> of factors that Allwinner and us are using for audio.
>
> Hu? What do you mean by that?
PLL2 (aka PLL2x1) is 24 * N / pre / post
PLL2x8 is 24 * 2 * N / pre
So PLL2 * 8 == PLL2x8 only if post == 4, which holds true on our
software implementation as well as AW's, but may not always hold true
hardware wise.
next prev parent reply other threads:[~2014-08-04 20:23 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-31 21:28 [PATCH 0/9] Audio clocks for sun[457]i, SoC revision detection Emilio López
2014-07-31 21:28 ` [PATCH 1/9] ARM: sunxi: introduce SoC identification support Emilio López
2014-08-03 12:40 ` Maxime Ripard
2014-08-03 21:45 ` Emilio López
2014-08-04 8:08 ` Lee Jones
2014-08-04 19:48 ` Maxime Ripard
2014-07-31 21:28 ` [PATCH 2/9] ARM: sunxi: quirk support Emilio López
2014-08-03 12:42 ` Maxime Ripard
2014-08-03 21:37 ` Emilio López
2014-08-04 19:32 ` Maxime Ripard
2014-07-31 21:28 ` [PATCH 3/9] ARM: sunxi: make sun6i SMP ops static Emilio López
2014-08-03 12:41 ` Maxime Ripard
2014-07-31 21:28 ` [PATCH 4/9] clk: sunxi: PLL2 support for sun4i, sun5i and sun7i Emilio López
2014-08-03 12:44 ` Maxime Ripard
2014-08-03 15:58 ` Chen-Yu Tsai
2014-08-03 18:48 ` Maxime Ripard
2014-08-03 22:02 ` Emilio López
2014-08-04 20:02 ` Maxime Ripard
2014-08-04 20:23 ` Emilio López [this message]
2014-08-07 11:23 ` Maxime Ripard
2014-08-06 13:51 ` jonsmirl at gmail.com
2014-08-06 15:20 ` jonsmirl at gmail.com
2014-08-08 0:03 ` jonsmirl at gmail.com
2014-07-31 21:28 ` [PATCH 5/9] clk: sunxi: codec clock support Emilio López
2014-07-31 21:28 ` [PATCH 6/9] clk: sunxi: mod1 " Emilio López
2014-08-03 12:47 ` Maxime Ripard
2014-08-03 22:11 ` Emilio López
2014-08-04 19:52 ` Maxime Ripard
2014-07-31 21:28 ` [PATCH 7/9] ARM: sunxi: dt: Add PLL2 support Emilio López
2014-07-31 21:46 ` jonsmirl at gmail.com
2014-08-03 12:50 ` Maxime Ripard
2014-08-03 15:55 ` Chen-Yu Tsai
2014-08-03 22:15 ` Emilio López
2014-08-04 19:53 ` Maxime Ripard
2014-07-31 21:28 ` [PATCH 8/9] ARM: sunxi: dt: Add codec clock support Emilio López
2014-07-31 21:28 ` [PATCH 9/9] ARM: sun7i: dt: Add mod1 clock nodes Emilio López
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