linux-kernel - Re: [PATCH v7 6/7] clk: hi6220: Clock driver support for Hisilicon hi6220 SoC

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Date:	Thu, 21 May 2015 11:00:53 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Bintian <bintian.wang@...wei.com>, mturquette@...aro.org,
	zhangfei.gao@...aro.org, xuwei5@...ilicon.com,
	xuejiancheng@...wei.com, tomeu.vizoso@...labora.com,
	sledge.yanwei@...wei.com, linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org, arnd@...db.de, will.deacon@....com,
	robh+dt@...nel.org, khilman@...aro.org, mark.rutland@....com,
	catalin.marinas@....com, haojian.zhuang@...aro.org,
	linux-arm-kernel@...ts.infradead.org, olof@...om.net,
	yanhaifeng@...il.com, linux@....linux.org.uk,
	guodong.xu@...aro.org, jorge.ramirez-ortiz@...aro.org,
	tyler.baker@...aro.org, khilman@...nel.org
CC:	xuyiping@...ilicon.com, wangbinghui@...ilicon.com,
	zhenwei.wang@...ilicon.com, victor.lixin@...ilicon.com,
	puck.chen@...ilicon.com, dan.zhao@...ilicon.com,
	huxinwei@...wei.com, z.liuxinliang@...wei.com, heyunlei@...wei.com,
	kong.kongxinwei@...ilicon.com, wangbintian@...il.com,
	w.f@...wei.com, liguozhu@...ilicon.com
Subject: Re: [PATCH v7 6/7] clk: hi6220: Clock driver support for Hisilicon
 hi6220 SoC

On 05/20/15 20:57, Bintian wrote:
>
>>
>>>
>>> +
>>> +static void __init hi6220_clk_sys_init(struct device_node *np)
>>> +{
>>> +    struct hisi_clock_data *clk_data;
>>> +
>>> +    clk_data = hisi_clk_init(np, HI6220_SYS_NR_CLKS);
>>> +    if (!clk_data)
>>> +        return;
>>> +
>>> +    hisi_clk_register_gate_sep(hi6220_separated_gate_clks_sys,
>>> +            ARRAY_SIZE(hi6220_separated_gate_clks_sys), clk_data);
>>> +
>>> +    hisi_clk_register_mux(hi6220_mux_clks_sys,
>>> +            ARRAY_SIZE(hi6220_mux_clks_sys), clk_data);
>>> +
>>> +    hi6220_clk_register_divider(hi6220_div_clks_sys,
>>> +            ARRAY_SIZE(hi6220_div_clks_sys), clk_data);
>>> +
>>> +    if (!clk_data_ao)
>>> +        return;
>>> +
>>> +    /* enable high speed clock on UART1 mux */
>>> +    clk_set_parent(clk_data->clk_data.clks[HI6220_UART1_SRC],
>>> +            clk_data_ao->clk_data.clks[HI6220_150M]);
>>
>> Sorry I missed this one earlier. Can we do this clk_set_parent() through
>> assigned-parents instead?
> Uart1 has two clock parents in hi6220, and use "clk_tcxo" by default,
> we use uart1 to connect BT in HiKey, and switch to "clk_150m" for high
> speed mode of BT, but pl011 has no code to set clock rate or set clock
> parents operation, so it's a easy way to do that here.

Is pl011 the uart device? Does it have a node in DT somewhere? If it
does, then we could put the assigned-parents properties in that node so
that when the pl011 probes the uart1 clock has its parent set to
clk_150m. See the "Assigned clock parents and rates" section of
Documentation/devicetree/bindings/clock/clock-bindings.txt.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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