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Date:   Mon, 14 Jun 2021 11:50:43 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Alexander Sverdlin <alexander.sverdlin@gmail.com>
Cc:     Geert Uytterhoeven <geert@linux-m68k.org>,
        Nikita Shubin <nikita.shubin@maquefel.me>,
        linux-iio@vger.kernel.org, Lars-Peter Clausen <lars@metafoo.de>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/7] iio: ep93xx: Prepare clock before using it
Message-ID: <20210614115043.07ea0ae1@jic23-huawei>
In-Reply-To: <20210613233041.128961-2-alexander.sverdlin@gmail.com>
References: <20210613233041.128961-1-alexander.sverdlin@gmail.com>
        <20210613233041.128961-2-alexander.sverdlin@gmail.com>
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On Mon, 14 Jun 2021 01:30:35 +0200
Alexander Sverdlin <alexander.sverdlin@gmail.com> wrote:

> Use clk_prepare_enable()/clk_disable_unprepare() in preparation for switch
> to Common Clock Framework, otherwise the following is visible:
> 
> WARNING: CPU: 0 PID: 1 at drivers/clk/clk.c:1011 clk_core_enable+0x9c/0xbc
> Enabling unprepared ep93xx-adc
> CPU: 0 PID: 1 Comm: swapper Not tainted 5.13.0-rc5-... #1
> Hardware name: Cirrus Logic EDB9302 Evaluation Board
> [<c000d5b0>] (unwind_backtrace) from [<c000c590>] (show_stack+0x10/0x18)
> [<c000c590>] (show_stack) from [<c03a5f38>] (dump_stack+0x20/0x2c)
> [<c03a5f38>] (dump_stack) from [<c03a2098>] (__warn+0x98/0xc0)
> [<c03a2098>] (__warn) from [<c03a2150>] (warn_slowpath_fmt+0x90/0xc0)
> [<c03a2150>] (warn_slowpath_fmt) from [<c01d8358>] (clk_core_enable+0x9c/0xbc)
> [<c01d8358>] (clk_core_enable) from [<c01d8698>] (clk_core_enable_lock+0x18/0x30)
> [<c01d8698>] (clk_core_enable_lock) from [<c0266560>] (ep93xx_adc_probe+0xe4/0x1a0)
> [<c0266560>] (ep93xx_adc_probe) from [<c02126e0>] (platform_probe+0x34/0x80)
> [<c02126e0>] (platform_probe) from [<c0210bf8>] (really_probe+0xe8/0x394)
> [<c0210bf8>] (really_probe) from [<c0211464>] (device_driver_attach+0x5c/0x64)
> [<c0211464>] (device_driver_attach) from [<c02114e8>] (__driver_attach+0x7c/0xec)
> [<c02114e8>] (__driver_attach) from [<c020f1b4>] (bus_for_each_dev+0x78/0xc4)
> [<c020f1b4>] (bus_for_each_dev) from [<c0211570>] (driver_attach+0x18/0x24)
> [<c0211570>] (driver_attach) from [<c020fab4>] (bus_add_driver+0x140/0x1cc)
> [<c020fab4>] (bus_add_driver) from [<c0211c44>] (driver_register+0x74/0x114)
> [<c0211c44>] (driver_register) from [<c02134f8>] (__platform_driver_register+0x18/0x24)
> [<c02134f8>] (__platform_driver_register) from [<c0470148>] (ep93xx_adc_driver_init+0x10/0x1c)
> [<c0470148>] (ep93xx_adc_driver_init) from [<c045ce88>] (do_one_initcall+0x7c/0x1a4)
> [<c045ce88>] (do_one_initcall) from [<c045d184>] (kernel_init_freeable+0x17c/0x1fc)
> [<c045d184>] (kernel_init_freeable) from [<c03a64d0>] (kernel_init+0x8/0xf8)
> [<c03a64d0>] (kernel_init) from [<c00082d8>] (ret_from_fork+0x14/0x3c)
> ...
> ep93xx-adc ep93xx-adc: Cannot enable clock
> ep93xx-adc: probe of ep93xx-adc failed with error -108
> 
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

>From cover letter I'm assuming you want these to go through same route as
the common clock conversion?  If not shout and I can pick this one up.

Jonathan

> ---
>  drivers/iio/adc/ep93xx_adc.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/ep93xx_adc.c b/drivers/iio/adc/ep93xx_adc.c
> index c08ab3c6dfaf..5c85257b814c 100644
> --- a/drivers/iio/adc/ep93xx_adc.c
> +++ b/drivers/iio/adc/ep93xx_adc.c
> @@ -207,7 +207,7 @@ static int ep93xx_adc_probe(struct platform_device *pdev)
>  		 */
>  	}
>  
> -	ret = clk_enable(priv->clk);
> +	ret = clk_prepare_enable(priv->clk);
>  	if (ret) {
>  		dev_err(&pdev->dev, "Cannot enable clock\n");
>  		return ret;
> @@ -215,7 +215,7 @@ static int ep93xx_adc_probe(struct platform_device *pdev)
>  
>  	ret = iio_device_register(iiodev);
>  	if (ret)
> -		clk_disable(priv->clk);
> +		clk_disable_unprepare(priv->clk);
>  
>  	return ret;
>  }
> @@ -226,7 +226,7 @@ static int ep93xx_adc_remove(struct platform_device *pdev)
>  	struct ep93xx_adc_priv *priv = iio_priv(iiodev);
>  
>  	iio_device_unregister(iiodev);
> -	clk_disable(priv->clk);
> +	clk_disable_unprepare(priv->clk);
>  
>  	return 0;
>  }