On Mon, Oct 1, 2012 at 11:22 AM, Gwendal Grignou <gwendal@xxxxxxxxxx> wrote: > This set of patches improve ATA transport classes integration with SCSI > objects. > > Before [2.6.x] > > Ata and scsi transport class where separated: > `--0000:09:00.0 > | `--ata1 > | | `--port_port > | | `--link1 > | | | `--dev1.0 > | | | `--dev1.1 > | `--ata2 > | ... > | `--host0 > | | `--scsi_host > | | | `--host0 > | | `--target0:0:0 > | | | `--0:0:0:0 > | | | | `--block > | | | | | `--sda > | | | | | | `--sda1 > > In 3.2, Lin - in commit 9a6d6a2ddabbd32c07f6a38b659e5f3db319fa5a - addressed > the issue of linking the ata port with the scsi host object by placing the > scsi_host object under ata port objects. > > However to be more consistent with other transport, this patch does the opposite: > > For instance, with SAS transport, We have > `--0000:0b:00.0 > | `--host6 > | | `--phy-6:0 > | | `--phy-6:1 > ... > | | `--port-6:0 > | | | `--end_device-6:0 > | | | | `--sas_device > | | | | | `--end_device-6:0 > | | | | `--sas_end_device > | | | | | `--end_device-6:0 > | | | | `--target6:0:0 > | | | | | `--6:0:0:0 > | | | | | | `--block > | | | | | | | `--sdb > ... > | | `--port-6:1 > | | | `--end_device-6:1 > ... > phy and port have to be separated, sas_port are created dynamically. > > For ata, all objects are created at initialization time, so the layout is: > `--0000:09:00.0 > | `--host0 > | | `--port1 > | | | `--link1 > | | | | `--dev1.0 > | | | | | `--target0:0:0 > | | | | | | `--0:0:0:0 > | | | | | | | `--block > | | | | | | | | `--sda > > If we have a port multiplier, more links are created. > `--0000:09:00.0 > ... > | `--host4 > | | `--port5 > | | | `--link5 > | | | | `--dev5.0 > [device for the port multiplier] > | | | `--link5.0 > | | | | `--dev5.0.0 > | | | | | `--target4:0:0 > | | | | | | `--4:0:0:0 > | | | | | | | `--block > | | | | | | | | `--sdc > [disk in port 0 of the port multiplier] > ... > | | | `--link5.2 > | | | | `--dev5.2.0 > | | | | | `--target4:2:0 > | | | | | | `--4:2:0:0 > | | | | | | | `--block > | | | | | | | | `--sde > [disk in port 2 of the port multiplier] > > In consequence, the path of a scsi device becomes: > .../0000:00:1f.2/host0/port1/link1/dev1.0/target0:0:0/0:0:0:0 > dev1.0 indicates the master device [0] in ata port 1. > ata1 being under host0, we know the reliationships between the scsi_host id and > ata port id. > > or when a port multiplier is present: for instance the device in port 4 of the > port multiplier: > .../0000:00:06.0/0000:09:00.0/host5/port6/link6.4/dev6.4.0/target5:4:0/5:4:0:0 What's the benefit of this? From a PM perspective now it seems we'll have the parent hardware port suspended before all the scsi_hosts on that port, which defeats the original purpose of putting the ata_port in the PM hierarchy. -- Dan -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
