On Wed, Apr 21, 2021 at 3:57 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> Hello Oscar Salvador,
>
> The patch bfb96e4c344e: "drm/nouveau/hwmon: Remove old code, add
> .write/.read operations" from May 18, 2017, leads to the following
> static checker warning:
>
> drivers/gpu/drm/nouveau/nouveau_hwmon.c:507 nouveau_in_read()
> warn: check sign expansion for '-19'
> drivers/gpu/drm/nouveau/nouveau_hwmon.c:510 nouveau_in_read()
> warn: check sign expansion for '-19'
>
> drivers/gpu/drm/nouveau/nouveau_hwmon.c
> 488 static int
> 489 nouveau_in_read(struct device *dev, u32 attr, int channel, long *val)
> 490 {
> 491 struct drm_device *drm_dev = dev_get_drvdata(dev);
> 492 struct nouveau_drm *drm = nouveau_drm(drm_dev);
> 493 struct nvkm_volt *volt = nvxx_volt(&drm->client.device);
> 494 int ret;
> 495
> 496 if (!volt)
> 497 return -EOPNOTSUPP;
> 498
> 499 switch (attr) {
> 500 case hwmon_in_input:
> 501 if (drm_dev->switch_power_state != DRM_SWITCH_POWER_ON)
> 502 return -EINVAL;
> 503 ret = nvkm_volt_get(volt);
> 504 *val = ret < 0 ? ret : (ret / 1000);
> 505 break;
> 506 case hwmon_in_min:
> 507 *val = volt->min_uv > 0 ? (volt->min_uv / 1000) : -ENODEV;
>
> This is trying to set "*val = -ENODEV" but because "volt->min_uv" is
> unsigned int it actually sets it to "*val = (unsigned int)-ENODEV".
>
> It's weird to me that this code doesn't return -ENODEV instead of
> setting *val to it.
>
ohh.. that might actually be a left over from the conversion we've
done in the past. Thanks for pointing it out. Do you want to write the
patch as well?
> 508 break;
> 509 case hwmon_in_max:
> 510 *val = volt->max_uv > 0 ? (volt->max_uv / 1000) : -ENODEV;
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> 511 break;
> 512 default:
> 513 return -EOPNOTSUPP;
> 514 }
> 515
> 516 return 0;
> 517 }
>
> regards,
> dan carpenter
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