Re: [PATCH v2] clk: imx7d: do not set parent of ethernet time/ref clocks
From: Fabio Estevam
Date: Mon Jul 11 2016 - 22:15:59 EST
On Wed, Jul 6, 2016 at 9:53 PM, Michael Turquette
> 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@xxxxxxxx>
I still don't see this patch applied in clk-next.