linux-kernel - Re: [PATCH v2 06/10] clk: berlin: add core clock driver for BG2/BG2CD

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Date:	Thu, 15 May 2014 17:43:03 +0200
From:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
CC:	Mike Turquette <mturquette@...aro.org>,
	Jisheng Zhang <jszhang@...vell.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 06/10] clk: berlin: add core clock driver for BG2/BG2CD

On 05/15/2014 10:09 AM, Alexandre Belloni wrote:
> On 14/05/2014 at 22:15:17 +0200, Sebastian Hesselbarth wrote :
>> +	/* clock divider cells */
>> +	parent_names[1] = avpllb_names[CH4];
>> +	parent_names[2] = avpllb_names[CH5];
>> +	parent_names[3] = avpllb_names[CH6];
>> +	parent_names[4] = avpllb_names[CH7];
>> +
>> +	parent_names[0] = refclk_names[SYSPLL];
>
> It should actually be:
>
> parent_names[0] = avpllb_names[CH4];
> parent_names[1] = avpllb_names[CH5];
> parent_names[2] = avpllb_names[CH6];
> parent_names[3] = avpllb_names[CH7];
> parent_names[4] = refclk_names[SYSPLL];

Given the comment to remove index 0 in the last patch, I translate that
into: "the input mux bypass is there, but {cannot,should not,we do not
want it to} be used". *sigh*

Actually, almost all of this is based on Chromecast mirrored BSP code
and I though about leaving the bypass mux in - even if it is not used
at all.

The reason is that I am _very_ tired of reading through the BSP code
and have all the things in mind where the BSP code is unclear.

>> +	data = &bg2_divs[CLKID_SYS];
>> +	clks[CLKID_SYS] = berlin2_div_register(&data->map, base, data->name,
>> +		       data->div_flags, parent_names, 5, data->flags, &lock);
>> +
>> +	parent_names[0] = refclk_names[CPUPLL];
>> +	parent_names[5] = refclk_names[MEMPLL];
>
> The only valid choice here should be (remember, we are not adding 1 to
> the index anymore):
> parent_names[4] = refclk_names[MEMPLL];

Funny to see that there ought to be a CPUPLL which isn't used by the
CPU at all. This also implies to remove CPUPLL, right?

>> +	data = &bg2_divs[CLKID_CPU];
>> +	clks[CLKID_CPU] = berlin2_div_register(&data->map, base, data->name,
>> +			 data->div_flags, parent_names, 6, data->flags, &lock);
>> +
>
> This is where it gets tricky, now we should have:
> parent_names[0] = avpllb_names[CH4];
> parent_names[1] = avplla_names[CH5];
> parent_names[2] = avpllb_names[CH6];
> parent_names[3] = avpllb_names[CH7];
> parent_names[4] = refclk_names[SYSPLL];

First I thought that it is just the default input mux clocks again..
but then I noticed that it is actually AVPLL_A5 not B5.

Ok, I admit having confirmed information is maybe better. So, you agree
that we can remove the input mux bypass on the complex divider, too?
(Including all the consequences: remove it from the divmap, driver, ...)

Sebastian

>> +	parent_names[0] = refclk_names[SYSPLL];
>> +	for (n = CLKID_DRMFIGO; n <= CLKID_APP; n++) {
>> +		data = &bg2_divs[n];
>> +		clks[n] = berlin2_div_register(&data->map, base, data->name,
>> +			 data->div_flags, parent_names, 5, data->flags, &lock);
>> +	}
>> +
>

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