linux-kernel - Re: [PATCH v1 1/1] mfd: intel-lpss: save register context on suspend

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Message-ID: <20160308044823.GJ13692@x1>
Date:	Tue, 8 Mar 2016 11:48:23 +0700
From:	Lee Jones <lee.jones@...aro.org>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH v1 1/1] mfd: intel-lpss: save register context on suspend

On Tue, 26 Jan 2016, Andy Shevchenko wrote:

> From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> 
> All configurations are lost and the registers will have
> default values when the hardware is suspended and resumed,
> so saving the private register space context on suspend, and
> restoring it on resume.
> 
> Fixes: 4b45efe85263 (mfd: Add support for Intel Sunrisepoint LPSS devices)

I'd say this sumbission is more of a functional extention than a
bug-fix.  No real need for this statement.

> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>

Did it really take 2 of you to write this patch?

> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/mfd/intel-lpss.c | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)

Code looks okay though:
  Acked-by: Lee Jones <lee.jones@...aro.org>

> diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c
> index 1743788..2a7c6a7 100644
> --- a/drivers/mfd/intel-lpss.c
> +++ b/drivers/mfd/intel-lpss.c
> @@ -34,6 +34,7 @@
>  #define LPSS_DEV_SIZE		0x200
>  #define LPSS_PRIV_OFFSET	0x200
>  #define LPSS_PRIV_SIZE		0x100
> +#define LPSS_PRIV_REG_COUNT	(LPSS_PRIV_SIZE / 4)
>  #define LPSS_IDMA64_OFFSET	0x800
>  #define LPSS_IDMA64_SIZE	0x800
>  
> @@ -76,6 +77,7 @@ struct intel_lpss {
>  	struct mfd_cell *cell;
>  	struct device *dev;
>  	void __iomem *priv;
> +	u32 priv_ctx[LPSS_PRIV_REG_COUNT];
>  	int devid;
>  	u32 caps;
>  	u32 active_ltr;
> @@ -492,6 +494,16 @@ EXPORT_SYMBOL_GPL(intel_lpss_prepare);
>  
>  int intel_lpss_suspend(struct device *dev)
>  {
> +	struct intel_lpss *lpss = dev_get_drvdata(dev);
> +	unsigned int i;
> +
> +	/* Save device context */
> +	for (i = 0; i < LPSS_PRIV_REG_COUNT; i++)
> +		lpss->priv_ctx[i] = readl(lpss->priv + i * 4);
> +
> +	/* Put the device into reset state */
> +	writel(0, lpss->priv + LPSS_PRIV_RESETS);
> +
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(intel_lpss_suspend);
> @@ -499,8 +511,13 @@ EXPORT_SYMBOL_GPL(intel_lpss_suspend);
>  int intel_lpss_resume(struct device *dev)
>  {
>  	struct intel_lpss *lpss = dev_get_drvdata(dev);
> +	unsigned int i;
>  
> -	intel_lpss_init_dev(lpss);
> +	intel_lpss_deassert_reset(lpss);
> +
> +	/* Restore device context */
> +	for (i = 0; i < LPSS_PRIV_REG_COUNT; i++)
> +		writel(lpss->priv_ctx[i], lpss->priv + i * 4);
>  
>  	return 0;
>  }

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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