Re: [PATCH v1] drm/i915/hwmon: expose package temperature

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Wed, Aug 28, 2024 at 10:15:12AM +0530, Raag Jadav wrote:
> Add hwmon support for temp1_input attribute, which will expose package
> temperature in millidegree Celsius. With this in place we can monitor
> package temperature using lm-sensors tool.
> 
> $ sensors
> i915-pci-0300
> Adapter: PCI adapter
> in0:         990.00 mV
> fan1:        1260 RPM
> temp1:        +45.0°C
> power1:           N/A  (max =  35.00 W)
> energy1:      12.62 kJ

...

> +static umode_t
> +hwm_temp_is_visible(const struct hwm_drvdata *ddat, u32 attr)
> +{
> +	struct i915_hwmon *hwmon = ddat->hwmon;
> +
> +	if (attr == hwmon_temp_input && i915_mmio_reg_valid(hwmon->rg.pkg_temp))
> +		return 0444;
> +
> +	return 0;

Just a question (I'm fine with this implementation): is the style in this file
to check for correct cases first and return an err/etc at the end?

> +}
> +
> +static int
> +hwm_temp_read(struct hwm_drvdata *ddat, u32 attr, long *val)
> +{
> +	struct i915_hwmon *hwmon = ddat->hwmon;
> +	intel_wakeref_t wakeref;
> +	u32 reg_val;
> +
> +	if (attr == hwmon_temp_input) {
> +		with_intel_runtime_pm(ddat->uncore->rpm, wakeref)
> +			reg_val = intel_uncore_read(ddat->uncore, hwmon->rg.pkg_temp);
> +
> +		/* HW register value is in degrees, convert to millidegrees. */
> +		*val = REG_FIELD_GET(TEMP_MASK, reg_val) * MILLIDEGREE_PER_DEGREE;
> +		return 0;
> +	}

...because here we may drop an indentation level by doing it opposite

	if (x != y)
		return -E...;

	...

> +	return -EOPNOTSUPP;
> +}

-- 
With Best Regards,
Andy Shevchenko