Kristen Carlson Accardi wrote:
power off unused ports
If the port isn't either a drive bay or an external SATA port, do not
keep the phy powered on if the port is unoccupied. This saves .75 watts
on most laptops. A module parameter can be used to override this
behavior and allow the phy's to be powered up regardless of whether it
has externally accessible SATA ports.
Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@xxxxxxxxx>
..
+static void ata_phy_offline(struct ata_link *link)
+{
+ u32 scontrol;
+ int rc;
+
+ /* set DET to 4 */
+ rc = sata_scr_read(link, SCR_CONTROL, &scontrol);
+ if (rc)
+ return;
+ scontrol &= ~0xf;
+ scontrol |= (1 << 2);
+ sata_scr_write(link, SCR_CONTROL, scontrol);
+}
..
I don't like to be picky, but we already have an "ata_link_offline"
function in libata, which tests *whether* a link is offline,
as opposed to *setting* a link to be offline.
So in that context, I find the name ata_phy_offline slightly confusing.
Perhaps something like ata_set_phy_offline would make it more clear?
And a more general note: I still believe we should have a follow-up
feature to this one, to enable polling for newly inserted drives.
That would allow powering down idle ports to save money/planet/whatever,
but still with hotplug capability. The polling interval should be
tunable in /sys, with a default of, say, once every couple of seconds.
Thanks for working on this stuff.
Cheers
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