Tejun Heo writes: ... > > 4. What are these "internal commands" that map to ATA_TAG_INTERNAL? > > Are they NCQ or not? > > Does the existence of ATA_TAG_INTERNAL limit queue depth for NCQ? > > Yeah, it reserves tag 31 for EH commands. We might as well use tag 32 > for EH commands and let LLD map it to whatever tag it can use for EH > commands but Jeff didn't like using all the tags as it makes 0xffffffff > a valid status value. > > Note that depending on LLD implementation, you might want to remap tag > 31 to different hardware tag. sata_sil24 does this mainly because it > made polled execution implementation easier. I think I'll remap them to 0 too. The tag ends up in a field in the ATA packet header that's overloaded for NCQ tags and non-NCQ packet "delay sequence ids". So far sata_promise has always set this field to 0, and set up seqid #0 as /dev/null, so I'm not comfortable allowing non-zero values into this field for non-NCQ packets. Thanks, /Mikael -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
