On Tue, Sep 20, 2022 at 06:24:58AM +0000, Tian, Kevin wrote: > External email: Use caution opening links or attachments > > > > From: Nicolin Chen <nicolinc@xxxxxxxxxx> > > Sent: Thursday, September 15, 2022 3:54 PM > > > > +/** > > + * iommu_attach_device - Attach a device to an IOMMU domain > > + * @domain: IOMMU domain to attach > > + * @dev: Device that will be attached > > + * > > + * Returns 0 on success and error code on failure > > + * > > + * Note that EINVAL may be returned as a soft failure if the domain and > > device > > + * are incompatible: if the domain has already been used or configured in > > some > > I didn't get the meaning of the 'if' part. It means that the failure of attaching the device to the domain is due to the domain configuration. > > + * way, attaching the same device to a different domain may succeed. > > Otherwise, > > + * it may still represent some fundamental problem. > > I'm not sure what the sentence after 'otherwise' actually adds to the > caller. There is no way to differentiate incompatibility vs. fundamental > problem, hence pointless for the caller to know this fact. > > IMHO just state that the caller can treat -EINVAL as soft failure indicating > incompatibility issue between domain and device. OK. I changed to: + * Note that EINVAL may be returned as a soft failure if the domain and device + * are incompatible due to some previous configuration of the domain, in which + * case attaching the same device to a different domain may succeed. > Later for @attach_dev you can add that driver may return (but not > recommend) -EINVAL for some fundamental problems. OK.
