Re: [PATCH 1/2] clk: tegra: Fix warning caused by pll_u failing to lock

Rhyland Klein
2015-12-21T16:38:05Z

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@nvidia.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@nvidia.com>

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