linux-kernel - Re: [PATCH] mfd: tc6393xb fail ohci suspend if full state restore is required

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Message-ID: <20141103145623.GH4538@x1>
Date:	Mon, 3 Nov 2014 14:56:23 +0000
From:	Lee Jones <lee.jones@...aro.org>
To:	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>
Cc:	linux-kernel@...r.kernel.org, Samuel Ortiz <sameo@...ux.intel.com>,
	stable@...r.kernel.org
Subject: Re: [PATCH] mfd: tc6393xb fail ohci suspend if full state restore is
 required

On Fri, 24 Oct 2014, Dmitry Eremin-Solenikov wrote:

> Some boards with TC6393XB chip require full state restore during system
> resume thanks to chip's VCC being cut off during suspend (Sharp SL-6000
> tosa is one of them). Failing to do so would result in ohci Oops on
> resume due to internal memory contentes being changed. Fail ohci suspend
> on tc6393xb is full state restore is required.
> 
> Recommended workaround is to unbind tmio-ohci driver before suspend and
> rebind it after resume.
> 
> Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@...il.com>
> Cc: stable@...r.kernel.org
> ---
>  drivers/mfd/tc6393xb.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/tc6393xb.c b/drivers/mfd/tc6393xb.c
> index 11c19e5..48579e5 100644
> --- a/drivers/mfd/tc6393xb.c
> +++ b/drivers/mfd/tc6393xb.c
> @@ -263,6 +263,17 @@ static int tc6393xb_ohci_disable(struct platform_device *dev)
>  	return 0;
>  }
>  
> +static int tc6393xb_ohci_suspend(struct platform_device *dev)
> +{
> +	struct tc6393xb_platform_data *tcpd = dev_get_platdata(dev->dev.parent);
> +
> +	/* We can't properly store/restore OHCI state, so fail here */
> +	if (tcpd->resume_restore)
> +		return -EBUSY;

Wouldn't it be easier to just put these three lines into
tc6393xb_ohci_disable() instead off adding 7 superfluous lines and
making the Ops names inconsistent?


> +	return tc6393xb_ohci_disable(dev);
> +}
> +
>  static int tc6393xb_fb_enable(struct platform_device *dev)
>  {
>  	struct tc6393xb *tc6393xb = dev_get_drvdata(dev->dev.parent);
> @@ -403,7 +414,7 @@ static struct mfd_cell tc6393xb_cells[] = {
>  		.num_resources = ARRAY_SIZE(tc6393xb_ohci_resources),
>  		.resources = tc6393xb_ohci_resources,
>  		.enable = tc6393xb_ohci_enable,
> -		.suspend = tc6393xb_ohci_disable,
> +		.suspend = tc6393xb_ohci_suspend,
>  		.resume = tc6393xb_ohci_enable,
>  		.disable = tc6393xb_ohci_disable,
>  	},

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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