linux-kernel - Re: [PATCH v2] clk: imx7d: do not set parent of ethernet time/ref clocks

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Message-ID: <CAOMZO5CuLshhk9R3dJh9RjEG2FphV5Z+sALpb2FitmRkKrFPZA@mail.gmail.com>
Date:	Mon, 11 Jul 2016 23:15:54 -0300
From:	Fabio Estevam <festevam@...il.com>
To:	Michael Turquette <mturquette@...libre.com>
Cc:	Stefan Agner <stefan@...er.ch>,
	Dong Aisheng <aisheng.dong@....com>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <kernel@...gutronix.de>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Igor Grinberg <grinberg@...pulab.co.il>,
	Gary Bisson <gary.bisson@...ndarydevices.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>, linux-clk@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] clk: imx7d: do not set parent of ethernet time/ref clocks

Hi Mike,

On Wed, Jul 6, 2016 at 9:53 PM, Michael Turquette
<mturquette@...libre.com> wrote:
> Quoting Stefan Agner (2016-07-03 10:48:13)
>> All device trees currently in mainline specify the time clock parent
>> using the assigned-clocks/assigned-clock-parents method, there is no
>> need to statically assign the parent in the core clock driver.
>> Also all current boards provide an Ethernet reference clock for the
>> PHY externally, hence configuring the internal PHY reference clock.
>>
>> Furthermore, and the actual driver of this patch, specify ethernet
>> related parents at that early point in boot leads to a warning:
>> bad: scheduling from the idle thread!
>>
>> The reason for the warning is that setting the parent enables the ENET
>> PLL since we are using CLK_OPS_PARENT_ENABLE. Enabling the ENET PLL can
>> cause clk_pllv3_wait_lock to sleep. See also:
>> commit fc8726a2c021 ("clk: core: support clocks which requires parents
>> enable (part 2)").
>>
>> Note that setting the ENET AXI root clock parent also requires ENET
>> PLL to be enabled. However, U-Boot typically leaves the ENET PLL on,
>> hence when the framework sets the parent of the first clock, it does
>> not need to wait for the PLL to come up. But because there is currently
>> no user of that clock, the PLL gets disabled after setting the parent.
>> Therefore, subsequent reparenting calls of any clock which somehow rely
>> on the ENET PLL, need to reenable the ENET PLL which leads to a sleep.
>> Removing those subsequent reparenting calls works around this issue.
>>
>> Also remove comments. The code is really verbose enough.
>>
>> Signed-off-by: Stefan Agner <stefan@...er.ch>
>
> Applied.

I still don't see this patch applied in clk-next.