linux-kernel - Re: [PATCH 1/2] clk: tegra: Fix warning caused by pll

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Date:	Mon, 21 Dec 2015 11:37:59 -0500
From:	Rhyland Klein <rklein@...dia.com>
To:	Jon Hunter <jonathanh@...dia.com>,
	Peter De Schrijver <pdeschrijver@...dia.com>,
	Prashant Gaikwad <pgaikwad@...dia.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>
CC:	<linux-clk@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] clk: tegra: Fix warning caused by pll_u failing to
 lock

On 12/21/2015 7:56 AM, Jon Hunter wrote:
> If the pll_u is not configured by the bootloader, then on kernel boot the
> following warning is seen:
> 
>  clk_pll_wait_for_lock: Timed out waiting for pll pll_u_vco lock
>  tegra_init_from_table: Failed to enable pll_u_out1
>  ------------[ cut here ]------------
>  WARNING: at drivers/clk/tegra/clk.c:269
>  Modules linked in:
> 
>  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-rc4-next-20151214+ #1
>  Hardware name: NVIDIA Tegra210 P2371 reference board (E.1) (DT)
>  task: ffffffc0bc0a0000 ti: ffffffc0bc0a8000 task.ti: ffffffc0bc0a8000
>  PC is at tegra_init_from_table+0x140/0x164
>  LR is at tegra_init_from_table+0x140/0x164
>  pc : [<ffffffc0008fee78>] lr : [<ffffffc0008fee78>] pstate: 80000045
>  sp : ffffffc0bc0abd50
>  x29: ffffffc0bc0abd50 x28: ffffffc00090b8a8
>  x27: ffffffc000a06000 x26: ffffffc0bc019780
>  x25: ffffffc00086a708 x24: ffffffc00086a790
>  x23: ffffffc0006d7188 x22: ffffffc0bc010000
>  x21: 000000000000016e x20: ffffffc0bc00d100
>  x19: ffffffc000944178 x18: 0000000000000007
>  x17: 000000000000000e x16: 0000000000000001
>  x15: 0000000000000007 x14: 000000000000000e
>  x13: 0000000000000013 x12: 000000000000001a
>  x11: 000000000000004d x10: 0000000000000750
>  x9 : ffffffc0bc0a8000 x8 : ffffffc0bc0a07b0
>  x7 : 0000000000000001 x6 : 0000000002d5f0f8
>  x5 : 0000000000000000 x4 : 0000000000000000
>  x3 : 0000000000000002 x2 : ffffffc000996724
>  x1 : 0000000000000000 x0 : 0000000000000032
> 
>  ---[ end trace cbd20ae519e92ced ]---
>  Call trace:
>  [<ffffffc0008fee78>] tegra_init_from_table+0x140/0x164
>  [<ffffffc000900ac8>] tegra210_clock_apply_init_table+0x20/0x28
>  [<ffffffc0008fec40>] tegra_clocks_apply_init_table+0x18/0x24
>  [<ffffffc00008291c>] do_one_initcall+0x90/0x194
>  [<ffffffc0008cfab0>] kernel_init_freeable+0x148/0x1e8
>  [<ffffffc000636bb0>] kernel_init+0x10/0xdc
>  [<ffffffc000085cd0>] ret_from_fork+0x10/0x40
>  clk_pll_wait_for_lock: Timed out waiting for pll pll_u_vco lock
>  tegra_init_from_table: Failed to enable pll_u_out2
>  ------------[ cut here ]------------
> 
> pll_u can be either controlled by software or hardware and this is
> selected via the OVERRIDE bit in the pll_u base register. In the function
> tegra210_pll_init(), the OVERRIDE bit for pll_u is cleared, which selects
> hardware control of the pll. However, at the same time the pll_u clocks
> are populated in the init_table for tegra210 and so software will try to
> configure the pll_u if it is not already configured and hence, the above
> warning is seen when the pll fails to lock. Remove the pll_u clocks from
> the init_table so that software does not try to configure this pll on
> boot.
> 
> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
> ---
>  drivers/clk/tegra/clk-tegra210.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/clk/tegra/clk-tegra210.c b/drivers/clk/tegra/clk-tegra210.c
> index 849be30b52bf..791215747863 100644
> --- a/drivers/clk/tegra/clk-tegra210.c
> +++ b/drivers/clk/tegra/clk-tegra210.c
> @@ -2739,8 +2739,6 @@ static struct tegra_clk_init_table init_table[] __initdata = {
>  	{ TEGRA210_CLK_DFLL_REF, TEGRA210_CLK_PLL_P, 51000000, 1 },
>  	{ TEGRA210_CLK_SBC4, TEGRA210_CLK_PLL_P, 12000000, 1 },
>  	{ TEGRA210_CLK_PLL_RE_VCO, TEGRA210_CLK_CLK_MAX, 672000000, 1 },
> -	{ TEGRA210_CLK_PLL_U_OUT1, TEGRA210_CLK_CLK_MAX, 48000000, 1 },
> -	{ TEGRA210_CLK_PLL_U_OUT2, TEGRA210_CLK_CLK_MAX, 60000000, 1 },
>  	{ TEGRA210_CLK_XUSB_GATE, TEGRA210_CLK_CLK_MAX, 0, 1 },
>  	{ TEGRA210_CLK_XUSB_SS_SRC, TEGRA210_CLK_PLL_U_480M, 120000000, 0 },
>  	{ TEGRA210_CLK_XUSB_FS_SRC, TEGRA210_CLK_PLL_U_48M, 48000000, 0 },
> 

Acked-by: Rhyland Klein <rklein@...dia.com>

-- 
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