Re: [RESEND PATCH v2] thermal: tango: add resume support

[Thierry Reding <thierry.reding@gmail.com>]

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On Tue, Jun 28, 2016 at 01:37:58PM +0200, Mason wrote:
> From: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
> 
> When this platform is suspended, firmware powers the entire SoC down,
> except a few hardware blocks waiting for wakeup events. And there is
> no context to save for this particular block.
> 
> Therefore, there is nothing useful for the driver to do on suspend;
> so we define a NULL suspend hook. On resume, the driver initializes
> the block exactly as is done in the probe callback.
> 
> Reviewed-by: Kevin Hilman <khilman@baylibre.com>
> Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
> ---
> Add Kevin's Reviewed-by tag.
> Eduardo/Zhang, can you pick this patch up for 4.8?
> ---
>  drivers/thermal/tango_thermal.c | 27 +++++++++++++++++++++++++--
>  1 file changed, 25 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/thermal/tango_thermal.c b/drivers/thermal/tango_thermal.c
> index 70e0d9f406e9..d571ce2f546d 100644
> --- a/drivers/thermal/tango_thermal.c
> +++ b/drivers/thermal/tango_thermal.c
> @@ -64,6 +64,12 @@ static const struct thermal_zone_of_device_ops ops = {
>  	.get_temp	= tango_get_temp,
>  };
>  
> +static void tango_thermal_init(struct tango_thermal_priv *priv)
> +{
> +	writel(0, priv->base + TEMPSI_CFG);
> +	writel(CMD_ON, priv->base + TEMPSI_CMD);
> +}
> +
>  static int tango_thermal_probe(struct platform_device *pdev)
>  {
>  	struct resource *res;
> @@ -79,14 +85,30 @@ static int tango_thermal_probe(struct platform_device *pdev)
>  	if (IS_ERR(priv->base))
>  		return PTR_ERR(priv->base);
>  
> +	platform_set_drvdata(pdev, priv);
>  	priv->thresh_idx = IDX_MIN;
> -	writel(0, priv->base + TEMPSI_CFG);
> -	writel(CMD_ON, priv->base + TEMPSI_CMD);
> +	tango_thermal_init(priv);
>  
>  	tzdev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, priv, &ops);
>  	return PTR_ERR_OR_ZERO(tzdev);
>  }
>  
> +#ifdef CONFIG_PM_SLEEP
> +static int tango_thermal_resume(struct device *dev)
> +{
> +	struct tango_thermal_priv *priv = dev_get_drvdata(dev);
> +	tango_thermal_init(priv);

checkpatch will warn about this. You're supposed to separate the local
variable declarations and code by a single blank line.

> +
> +	return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(tango_thermal_pm, NULL, tango_thermal_resume);
> +
> +#define DEV_PM_OPS	&tango_thermal_pm
> +#else
> +#define DEV_PM_OPS	NULL
> +#endif

In my experience it's often not useful to #ifdef the struct pm_ops.
These days you almost certainly want PM enabled, and the conditional
doesn't save you all that much in the first place, because it's not
unlikely for this to fit into some of the space that would be padded
out anyway.

As a side-note, I've noticed that this driver has the following
dependencies:

	depends on ARCH_TANGO || COMPILE_TEST

which, last I checked, is probably going to fail on some architectures
because you need at least another one on HAS_IOMEM (for readl() and
writel()). That's a pre-existing problem, of course, so should be fixed
in a separate patch.

Thierry

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