linux-kernel - Re: [PATCH] i2c: i2c-qcom-geni: Fix runtime PM mismatch with child devices

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Date:   Fri, 2 Nov 2018 13:43:25 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Wolfram Sang <wsa@...-dreams.de>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        linux-i2c@...r.kernel.org, alokc@...eaurora.org,
        Evan Green <evgreen@...omium.org>
Subject: Re: [PATCH] i2c: i2c-qcom-geni: Fix runtime PM mismatch with child devices

Hi,

On Fri, Nov 2, 2018 at 11:35 AM Stephen Boyd <swboyd@...omium.org> wrote:
>
> We need to enable runtime PM on this i2c controller before populating
> child devices with i2c_add_adapter(). Otherwise, if a child device uses
> runtime PM and stays runtime PM enabled we'll get the following warning
> at boot.
>
>  Enabling runtime PM for inactive device (a98000.i2c) with active children
>  WARNING: CPU: 4 PID: 1 at drivers/base/power/runtime.c:1300 pm_runtime_enable+0xd8/0xf8
>  Modules linked in:
>  CPU: 4 PID: 1 Comm: swapper/0 Not tainted 4.19.0 #6
>  elants_i2c 14-0010: 14-0010 supply vccio not found, using dummy regulator
>  pstate: 60c00089 (nZCv daIf +PAN +UAO)
>  pc : pm_runtime_enable+0xd8/0xf8
>  lr : pm_runtime_enable+0xd8/0xf8
>  sp : ffffffc0de257a30
>  x29: ffffffc0de257a30 x28: 0000000000061a80
>  x27: ffffff9008ea7118
>  x26: ffffffc0d718b058
>  x25: ffffff9008ea7000 x24: ffffffc0d718a8dc
>  x23: ffffffc0d718a8b0 x22: ffffffc0d823dd58
>  x21: 0000000000000000 x20: ffffffc0d823dbc8
>  x19: ffffffc0d823da90 x18: 000000007f743d9a
>  x17: 0000000000000080 x16: 0000000000000003
>  x15: 000000000000003f x14: 0720072007200720
>  x13: 0720072007200720 x12: 0720072007200720
>  x11: 0720072007200720 x10: 0720072007200720
>  x9 : 0720072007200720 x8 : 0720072007200720
>  x7 : ffffff900816da30 x6 : 0000000000000000
>  x5 : 0000000000000080 x4 : 0000000000000003
>  x3 : ffffff900816f304 x2 : ffffffc0de248050
>  x1 : 25045a74f48a7400 x0 : 25045a74f48a7400
>  Call trace:
>   pm_runtime_enable+0xd8/0xf8
>   geni_i2c_probe+0x440/0x460
>   platform_drv_probe+0x74/0xc8
>   really_probe+0x1ac/0x35c
>   driver_probe_device+0xd4/0x118
>   __driver_attach+0xc8/0x118
>   bus_for_each_dev+0xac/0xe8
>   driver_attach+0x38/0x44
>   bus_add_driver+0x15c/0x294
>   driver_register+0x13c/0x198
>   __platform_driver_register+0x88/0x94
>   geni_i2c_driver_init+0x20/0x28
>   do_one_initcall+0x250/0x4ec
>   kernel_init_freeable+0x6f0/0x7c4
>   kernel_init+0x18/0x120
>   ret_from_fork+0x10/0x18
>
> Let's move the runtime PM enabling and setup to before we add the
> adapter, so that this device can respond to runtime PM requests from
> children.
>
> Cc: Douglas Anderson <dianders@...omium.org>
> Cc: Alok Chauhan <alokc@...eaurora.org>
> Fixes: 37692de5d523 ("i2c: i2c-qcom-geni: Add bus driver for the Qualcomm GENI I2C controller")
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> ---
>  drivers/i2c/busses/i2c-qcom-geni.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
> index 527f55c8c4c7..145eb98ac8b4 100644
> --- a/drivers/i2c/busses/i2c-qcom-geni.c
> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> @@ -571,18 +571,19 @@ static int geni_i2c_probe(struct platform_device *pdev)
>
>         dev_dbg(&pdev->dev, "i2c fifo/se-dma mode. fifo depth:%d\n", tx_depth);
>
> -       ret = i2c_add_adapter(&gi2c->adap);
> -       if (ret) {
> -               dev_err(&pdev->dev, "Error adding i2c adapter %d\n", ret);
> -               return ret;
> -       }
> -
>         gi2c->suspended = 1;
>         pm_runtime_set_suspended(gi2c->se.dev);
>         pm_runtime_set_autosuspend_delay(gi2c->se.dev, I2C_AUTO_SUSPEND_DELAY);
>         pm_runtime_use_autosuspend(gi2c->se.dev);
>         pm_runtime_enable(gi2c->se.dev);
>
> +       ret = i2c_add_adapter(&gi2c->adap);
> +       if (ret) {
> +               dev_err(&pdev->dev, "Error adding i2c adapter %d\n", ret);
> +               pm_runtime_disable(gi2c->se.dev);
> +               return ret;
> +       }
> +

Thanks for the fix.  It looks good, but can you also swap the
pm_runtime_disable() and i2c_del_adapter() calls in geni_i2c_remove()
to match?

-Doug