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Date: Wed, 11 Mar 2020 01:16:45 +0000
From: Peng Fan <peng.fan@....com>
To: Leonard Crestez <leonard.crestez@....com>,
"sboyd@...nel.org" <sboyd@...nel.org>,
Anson Huang <anson.huang@....com>
CC: "shawnguo@...nel.org" <shawnguo@...nel.org>,
"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
"festevam@...il.com" <festevam@...il.com>,
Abel Vesa <abel.vesa@....com>,
"kernel@...gutronix.de" <kernel@...gutronix.de>,
dl-linux-imx <linux-imx@....com>,
Aisheng Dong <aisheng.dong@....com>,
"linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Jacky Bai <ping.bai@....com>,
"l.stach@...gutronix.de" <l.stach@...gutronix.de>
Subject: RE: [PATCH RESEND v3 1/4] clk: imx: imx8mq: fix a53 cpu clock
> Subject: Re: [PATCH RESEND v3 1/4] clk: imx: imx8mq: fix a53 cpu clock
>
> On 19.02.2020 12:23, Peng Fan wrote:
> > From: Peng Fan <peng.fan@....com>
> >
> > The A53 CCM clk root only accepts input up to 1GHz, CCM A53 root
> > signoff timing is 1Ghz, however the A53 core which sources from CCM
> > root could run above 1GHz which violates the CCM.
> >
> > There is a CORE_SEL slice before A53 core, we need to configure the
> > CORE_SEL slice source from ARM PLL, not A53 CCM clk root.
> >
> > The A53 CCM clk root should only be used when need to change ARM PLL
> > frequency.
> >
> > Add arm_a53_core clk that could source from arm_a53_div and
> arm_pll_out.
> > Configure a53 ccm root sources from 800MHz sys pll Configure a53 core
> > sources from arm_pll_out Mark arm_a53_core as critical clock
> >
> > + clk_hw_set_parent(hws[IMX8MQ_CLK_A53_SRC],
> hws[IMX8MQ_SYS1_PLL_800M]);
> > + clk_hw_set_parent(hws[IMX8MQ_CLK_A53_CORE],
> > +hws[IMX8MQ_ARM_PLL_OUT]);
>
> This triggers lockdep warnings:
>
> [ 2.041743] ------------[ cut here ]------------
>
> [ 2.043531] WARNING: CPU: 2 PID: 1 at drivers/clk/clk.c:2480
> clk_core_set_parent_nolock+0x1d4/0x508
> [ 2.052584] Modules linked in:
>
> [ 2.055642] CPU: 2 PID: 1 Comm: swapper/0 Not tainted
> 5.6.0-rc4-next-20200306-00027-g6b7e51d87f22 #225
> [ 2.064966] Hardware name: NXP i.MX8MQ EVK (DT)
>
> [ 2.069504] pstate: 60000005 (nZCv daif -PAN -UAO)
>
> [ 2.074298] pc : clk_core_set_parent_nolock+0x1d4/0x508
>
> [ 2.079529] lr : clk_core_set_parent_nolock+0x1d0/0x508
>
>
> [ 2.084759] sp : ffff80001003b9b0
>
>
> [ 2.088072] x29: ffff80001003b9b0 x28: ffff8000116e8218
>
>
> [ 2.093392] x27: 0000000000004570 x26: ffff8000128745d0
>
>
> [ 2.098711] x25: ffff0000b8422008 x24: ffff0000b8422008
>
> [ 2.104030] x23: ffff80001104a518 x22: ffff80001104a508
>
> [ 2.109349] x21: ffff800012260bf8 x20: ffff0000b84c9600
>
> [ 2.114668] x19: ffff0000b84cbb00 x18: 0000000000004530
>
> [ 2.119987] x17: 0000000000004520 x16: 0000000000004510
>
>
> [ 2.125307] x15: 00000000000045d0 x14: 0000000000004500
>
>
> [ 2.130626] x13: 00000000000044f0 x12: 00000000000044e0
>
> [ 2.135945] x11: ffff8000116e6c68 x10: ffff8000117d7000
>
>
> [ 2.141264] x9 : ffff80001067007c x8 : 0000000000000000
>
> [ 2.146583] x7 : ffff800010671938 x6 : 0000000000000000
>
>
> [ 2.151903] x5 : ffff800011633000 x4 : 0000000000000000
>
> [ 2.157222] x3 : ffff80001003b804 x2 : 0000000000000000
>
>
> [ 2.162541] x1 : ffff0000b9da0000 x0 : 0000000000000000
>
> [ 2.167862] Call trace:
>
> [ 2.170307] clk_core_set_parent_nolock+0x1d4/0x508
>
> [ 2.175190] clk_hw_set_parent+0x1c/0x28
>
> [ 2.179114] imx8mq_clocks_probe+0x3538/0x3668
>
> [ 2.183562] platform_drv_probe+0x58/0xa8
>
> [ 2.187573] really_probe+0xe0/0x440
>
>
> [ 2.191145] driver_probe_device+0xe4/0x138
> [ 2.195333] device_driver_attach+0x74/0x80
>
>
> [ 2.199519] __driver_attach+0xa8/0x170
>
> [ 2.203354] bus_for_each_dev+0x74/0xc8
>
>
> [ 2.207190] driver_attach+0x28/0x30
>
> [ 2.210767] bus_add_driver+0x144/0x228
>
>
> [ 2.214605] driver_register+0x68/0x118
>
> [ 2.218438] __platform_driver_register+0x4c/0x58
>
>
> [ 2.223151] imx8mq_clk_driver_init+0x20/0x28
>
> [ 2.227511] do_one_initcall+0x88/0x410
>
> [ 2.231348] kernel_init_freeable+0x24c/0x2c0
>
> [ 2.235706] kernel_init+0x18/0x108
>
> [ 2.239192] ret_from_fork+0x10/0x18
>
> [ 2.242768] irq event stamp: 130084
>
> [ 2.246262] hardirqs last enabled at (130083): [<ffff800010302e78>]
> __slab_alloc.isra.0+0x90/0xb8
> [ 2.255241] hardirqs last disabled at (130084): [<ffff8000100a60b0>]
> do_debug_exception+0x168/0x254
> [ 2.264308] softirqs last enabled at (130070): [<ffff800010080e88>]
> __do_softirq+0x490/0x56c
> [ 2.272856] softirqs last disabled at (130057): [<ffff800010101e1c>]
> irq_exit+0x11c/0x148
> [ 2.281057] ---[ end trace 1fae73b5c77d8120 ]---
> [ 2.285792] ------------[ cut here ]------------
I not met such warning when I test, you enabled lockdep debug?
>
> This happens because clk_hw_set_parent does not take the prepare_lock so
> a lockdep_assert_held fails. In practice it should be mostly harmless because
> clk operations shouldn't happen while the SOC provider is probing.
>
> The issue can be worked around by doing the following instead:
>
> + clk_set_parent(hws[IMX8MQ_CLK_A53_SRC]->clk,
> hws[IMX8MQ_SYS1_PLL_800M]->clk);
> + clk_set_parent(hws[IMX8MQ_CLK_A53_CORE]->clk,
> hws[IMX8MQ_ARM_PLL_OUT]->clk);
>
> This implies reverting commit f95d58981f40 ("clk: imx: Include
> clk-provider.h instead of clk.h for i.MX8M SoCs clock driver") and
> somewhat rolls back the consumer/provider split.
>
> What would be a clean fix for this? It might make sense to add a new API.
>
How about moving this to dts? I'll give a try.
Thanks,
Peng.
> --
> Regards,
> Leonard
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