[U-Boot] [linux-sunxi] Re: [PATCH] sunxi: set up PLL1 on sun6i+ without use dividers

[icenowy at aosc.io]

在 2017-04-10 18:06，Ondřej Jirman 写道：
> Hi Maxime,
> 
> Maxime Ripard píše v Po 10. 04. 2017 v 08:59 +0200:
>> On Mon, Apr 10, 2017 at 12:19:41AM +0800, Icenowy Zheng wrote:
>> > According to the researching result of Ondrej Jirman, the factor M of
>> > PLL1 shouldn't be used and the factor P should be used only if the
>> > intended frequency is lower than 288MHz. This is proven by the
>> > clk-sun8iw7_tbl.c in the BSP source code -- in there the M value is
>> > always 0 and the maximum frequency that P is not 0 is 224MHz.
>> >
>> > As P is ignored on sun6i, it's not currently used. This patch removed
>> > the usage of M.
>> >
>> > This patch is an original work by Ondrej Jirman, however, he didn't add
>> > a Signed-off-by tag here to his commit. So I take this code and added my
>> > Signed-off-by.
>> >
>> > Signed-off-by: Icenowy Zheng <icenowy at aosc.io>
>> > ---
>> >
>> > This is a critical patch, and should be added to 2017.05.
>> >
>> > It has been verified by the Armbian.
>> 
>> This doesn't mean anything. How has this been verified?
> 
> We already discussed this here: https://patchwork.kernel.org/patch/9446
> 365/

P.S. as Chen-Yu dig out, it's not the correct work to restrict factors,
but we need to gate the PLL_CPUX when adjusting. (Of course the mux 
should
also be switched to osc24M when PLL_CPUX is gated)

I tried this on your h3-firmware code, and it succeeded with even P 
overused
(for any frequency) (and M is also free in this situation).

> 
> regards,
>   o.j.
> 
>> Maxime
>> 
>> --
>> Maxime Ripard, Free Electrons
>> Embedded Linux and Kernel engineering
>> http://free-electrons.com
>>