Subject: [PATCH] PM / Clocks: fix pm_clk_resume/suspend if CONFIG_PM_RUNTIME is set

From: [email-masked] (Stephen Boyd)
Date: Wed, 20 Nov 2013 10:42:30 -0800

On 11/20/13 05:31, Grygorii Strashko wrote:
> The following warning is shown and clk_enable() failed on Keystone platform
> if CONFIG_PM_RUNTIME is set and Runtime PM is enabled for Davinci gpio driver:
> [    0.564486] ------------[ cut here ]------------
> [    0.569221] WARNING: CPU: 0 PID: 1 at drivers/clk/clk.c:883__clk_enable+0x8c/0x98()
> [    0.577070] Modules linked in:
> [    0.580231] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.12.0-10116-g11d59938-dirty #259
> [    0.588368] [<c0014d34>] (unwind_backtrace+0x0/0xf8) from [<c0011eb8>] (show_stack+0x10/0x14)
> [    0.597018] [<c0011eb8>] (show_stack+0x10/0x14) from [<c03c5df0>] (dump_stack+0x64/0xa4)
> [    0.605235] [<c03c5df0>] (dump_stack+0x64/0xa4) from [<c00216b8>] (warn_slowpath_common+0x68/0x88)
> [    0.614315] [<c00216b8>] (warn_slowpath_common+0x68/0x88) from [<c00216f4>] (warn_slowpath_null+0x1c/0x24)
> [    0.624092] [<c00216f4>] (warn_slowpath_null+0x1c/0x24) from [<c0287a60>] (__clk_enable+0x8c/0x98)
> [    0.633173] [<c0287a60>] (__clk_enable+0x8c/0x98) from [<c0287c54>] (clk_enable+0x18/0x2c)
> [    0.641556] [<c0287c54>] (clk_enable+0x18/0x2c) from [<c023677c>] (pm_clk_resume+0x5c/0x80)
> [    0.650025] [<c023677c>] (pm_clk_resume+0x5c/0x80) from [<c001eba8>] (keystone_pm_runtime_resume+0xc/0x18)
> [    0.659800] [<c001eba8>] (keystone_pm_runtime_resume+0xc/0x18) from [<c02344e4>] (__rpm_callback+0x34/0x70)
> [    0.669662] [<c02344e4>] (__rpm_callback+0x34/0x70) from [<c0234548>] (rpm_callback+0x28/0x88)
> [    0.678390] [<c0234548>] (rpm_callback+0x28/0x88) from [<c023590c>] (rpm_resume+0x3c8/0x684)
> [    0.686942] [<c023590c>] (rpm_resume+0x3c8/0x684) from [<c0235e40>] (__pm_runtime_resume+0x4c/0x64)
> [    0.696111] [<c0235e40>] (__pm_runtime_resume+0x4c/0x64) from [<c0204798>] (davinci_gpio_probe+0x20c/0x5ac)
> [    0.705983] [<c0204798>] (davinci_gpio_probe+0x20c/0x5ac) from [<c02310cc>] (platform_drv_probe+0x18/0x48)
> [    0.715758] [<c02310cc>] (platform_drv_probe+0x18/0x48) from [<c022fa0c>] (driver_probe_device+0x80/0x21c)
> [    0.725532] [<c022fa0c>] (driver_probe_device+0x80/0x21c) from [<c022fc34>] (__driver_attach+0x8c/0x90)
> [    0.735044] [<c022fc34>] (__driver_attach+0x8c/0x90) from [<c022e35c>] (bus_for_each_dev+0x60/0x94)
> [    0.744207] [<c022e35c>] (bus_for_each_dev+0x60/0x94) from [<c022f24c>] (bus_add_driver+0xdc/0x1d0)
> [    0.753371] [<c022f24c>] (bus_add_driver+0xdc/0x1d0) from [<c023002c>] (driver_register+0x78/0xf4)
> [    0.762449] [<c023002c>] (driver_register+0x78/0xf4) from [<c00088fc>] (do_one_initcall+0xec/0x148)
> [    0.771616] [<c00088fc>] (do_one_initcall+0xec/0x148) from [<c0538c0c>] (kernel_init_freeable+0xfc/0x1c8)
> [    0.781303] [<c0538c0c>] (kernel_init_freeable+0xfc/0x1c8) from [<c03c19d0>] (kernel_init+0x8/0x110)
> [    0.790553] [<c03c19d0>] (kernel_init+0x8/0x110) from [<c000e318>] (ret_from_fork+0x14/0x3c)
> [    0.799117] ---[ end trace 6588a0ec7fbc847a ]---

Please omit the timestamps here.

>
> This happens because the clk_enable() is called without clk_prepare()
> from pm_clk_resume().
>
> Hence, switch to use clk_prepare_enable()/clk_disable_unprepare()
> instead of clk_enable()/clk_disable() in case if CONFIG_PM_RUNTIME is
> set.
> Actually, This is remainder fix of the earlier commit c122f27e1c
> "base: power - use clk_prepare_enable and clk_prepare_disable".
>
> Signed-off-by: Grygorii Strashko <[email-masked]>
> ---
>  drivers/base/power/clock_ops.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c
> index 9d8fde7..60d389a 100644
> --- a/drivers/base/power/clock_ops.c
> +++ b/drivers/base/power/clock_ops.c
> @@ -230,7 +230,7 @@ int pm_clk_suspend(struct device *dev)
>  	list_for_each_entry_reverse(ce, &psd->clock_list, node) {
>  		if (ce->status < PCE_STATUS_ERROR) {
>  			if (ce->status == PCE_STATUS_ENABLED)
> -				clk_disable(ce->clk);
> +				clk_disable_unprepare(ce->clk);
>  			ce->status = PCE_STATUS_ACQUIRED;
>  		}
>  	}
> @@ -259,7 +259,7 @@ int pm_clk_resume(struct device *dev)
>  
>  	list_for_each_entry(ce, &psd->clock_list, node) {
>  		if (ce->status < PCE_STATUS_ERROR) {
> -			clk_enable(ce->clk);
> +			clk_prepare_enable(ce->clk);
>  			ce->status = PCE_STATUS_ENABLED;
>  		}
>  	}

This is inside a spin_lock_irqsave(). You should be getting scheduling
while atomic warnings with this change. Are you testing with
DEBUG_ATOMIC_SLEEP=y?

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