Re: [PATCH 3/6] drm/nouveau: add GSP hwmon support

[lyude@redhat.com]

On Wed, 2026-07-15 at 01:14 +0400, Mohamed Ahmed wrote:
> +static int
> +nouveau_power_read(struct device *dev, u32 attr, int channel, long
> *val)
> +{
> +	struct drm_device *drm_dev = dev_get_drvdata(dev);
> +	struct nouveau_drm *drm = nouveau_drm(drm_dev);
> +	struct nvkm_iccsense *iccsense = nvxx_iccsense(drm);
> +	struct nvkm_device *device = drm->nvkm;
> +	struct nvkm_gsp *gsp = device->gsp;
> +
> +	if (nvkm_gsp_rusd(gsp))
> +		return nouveau_rusd_power_read(drm_dev, gsp, attr,
> channel, val);

IMO - let's add braces to this conditional

> +	else {
> +		if (!iccsense)
> +			return -EOPNOTSUPP;
> +
> +		switch (attr) {
> +		case hwmon_power_input:
> +			if (drm_dev->switch_power_state !=
> DRM_SWITCH_POWER_ON)
> +				return -EINVAL;
> +			*val = nvkm_iccsense_read_all(iccsense);
> +			break;
> +		case hwmon_power_max:
> +			*val = iccsense->power_w_max;
> +			break;
> +		case hwmon_power_crit:
> +			*val = iccsense->power_w_crit;
> +			break;
> +		default:
> +			return -EOPNOTSUPP;
> +		}
> +
> +		return 0;
> +	}
> +}
> +

...

>  static int
>  nouveau_temp_write(struct device *dev, u32 attr, int channel, long
> val)
>  {
> @@ -667,13 +854,39 @@ nouveau_hwmon_init(struct drm_device *dev)
>  	struct nvkm_iccsense *iccsense = nvxx_iccsense(drm);
>  	struct nvkm_therm *therm = nvxx_therm(drm);
>  	struct nvkm_volt *volt = nvxx_volt(drm);
> +	struct nvkm_device *device = drm->nvkm;
> +	struct nvkm_gsp *gsp = device->gsp;
>  	const struct attribute_group *special_groups[N_ATTR_GROUPS];
>  	struct nouveau_hwmon *hwmon;
>  	struct device *hwmon_dev;
> +	bool rusd_active = false;
>  	int ret = 0;
>  	int i = 0;
>  
> -	if (!iccsense && !therm && !volt) {
> +	if (nvkm_gsp_rusd(gsp)) {
> +		/* Per-channel visibility is latched below from live
> RUSD
> +		 * section validity, so wait for GSP-RM's first poll
> of both
> +		 * requested groups (thermal, power). It is normally
> completed
> +		 * long before we get here and this is a last
> resort.
> +		 */
> +		unsigned long timeout = jiffies +
> +			msecs_to_jiffies(2 * gsp->rusd.poll_ms);
> +		bool thermal, power;
> +
> +		for (;;) {
> +			thermal = nouveau_rusd_ok(gsp,
> NVKM_GSP_RUSD_TEMP_GPU);
> +			power = nouveau_rusd_ok(gsp,
> NVKM_GSP_RUSD_POWER_GPU) ||
> +				nouveau_rusd_ok(gsp,
> NVKM_GSP_RUSD_POWER_GPU_AVG) ||
> +				nouveau_rusd_ok(gsp,
> NVKM_GSP_RUSD_POWER_CAP);
> +			if ((thermal && power) ||
> !time_before(jiffies, timeout))
> +				break;
> +			msleep(20);
> +		}

Is it possible to use nvif_msec() here?

> +
> +		rusd_active = thermal || power;
> +	}
> +
> +	if (!iccsense && !therm && !volt && !rusd_active) {
>  		NV_DEBUG(drm, "Skipping hwmon registration\n");
>  		return 0;
>  	}