linux-kernel - Re: [PATCH] i2c: qup: Fix order of runtime pm initialization

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Date:	Mon, 29 Sep 2014 18:53:24 -0700
From:	Bjorn Andersson <bjorn.andersson@...ymobile.com>
To:	Andy Gross <agross@...eaurora.org>
CC:	Wolfram Sang <wsa@...-dreams.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"Ivan T. Ivanov" <iivanov@...sol.com>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] i2c: qup: Fix order of runtime pm initialization

On Mon 29 Sep 15:00 PDT 2014, Andy Gross wrote:

> The runtime pm calls need to be done before populating the children via the
> i2c_add_adapter call.  If this is not done, a child can run into issues trying
> to do i2c read/writes due to the pm_runtime_sync failing.
> 

May I ask in what case this would fail?  I thought we tested this as we found
the faulty error check after calling pm_runtime_get_sync().

Nontheless,

Acked-by: Bjorn Andersson <bjorn.andersson@...ymobile.com>

Regards,
Bjorn

> Signed-off-by: Andy Gross <agross@...eaurora.org>
> ---
>  drivers/i2c/busses/i2c-qup.c |   12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
> index 3a4d64e..092d89b 100644
> --- a/drivers/i2c/busses/i2c-qup.c
> +++ b/drivers/i2c/busses/i2c-qup.c
> @@ -674,16 +674,20 @@ static int qup_i2c_probe(struct platform_device *pdev)
>  	qup->adap.dev.of_node = pdev->dev.of_node;
>  	strlcpy(qup->adap.name, "QUP I2C adapter", sizeof(qup->adap.name));
>  
> -	ret = i2c_add_adapter(&qup->adap);
> -	if (ret)
> -		goto fail;
> -
>  	pm_runtime_set_autosuspend_delay(qup->dev, MSEC_PER_SEC);
>  	pm_runtime_use_autosuspend(qup->dev);
>  	pm_runtime_set_active(qup->dev);
>  	pm_runtime_enable(qup->dev);
> +
> +	ret = i2c_add_adapter(&qup->adap);
> +	if (ret)
> +		goto fail_runtime;
> +
>  	return 0;
>  
> +fail_runtime:
> +	pm_runtime_disable(qup->dev);
> +	pm_runtime_set_suspended(qup->dev);
>  fail:
>  	qup_i2c_disable_clocks(qup);
>  	return ret;
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> hosted by The Linux Foundation
> 
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