Messages in this thread | | | Date | Mon, 13 Nov 2006 10:32:24 -0500 | From | Jeff Garzik <> | Subject | Re: AHCI power saving (was Re: Ten hours on X60s) |
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Pavel Machek wrote: > --- a/drivers/ata/ahci.c > +++ b/drivers/ata/ahci.c > @@ -148,6 +148,8 @@ enum { > PORT_IRQ_PIOS_FIS | PORT_IRQ_D2H_REG_FIS, > > /* PORT_CMD bits */ > + PORT_CMD_ALPE = (1 << 27), /* Aggressive Link Power Management Enable */ > + PORT_CMD_ASP = (1 << 26), /* Aggressive entrance to Slumber or Partial power management states */ > PORT_CMD_ATAPI = (1 << 24), /* Device is ATAPI */ > PORT_CMD_LIST_ON = (1 << 15), /* cmd list DMA engine running */ > PORT_CMD_FIS_ON = (1 << 14), /* FIS DMA engine running */ > @@ -486,7 +488,7 @@ static void ahci_power_up(void __iomem * > } > > /* wake up link */ > - writel(cmd | PORT_CMD_ICC_ACTIVE, port_mmio + PORT_CMD); > + writel(cmd | PORT_CMD_ICC_ACTIVE | PORT_CMD_ALPE | PORT_CMD_ASP, port_mmio + PORT_CMD);
Therein lies a key problem. Turning on all of AHCI's aggressive power management features DOES save a lot of power. But at the same time, it shortens the life of your hard drive, particularly hard drives that are really PATA, but have a PATA<->SATA bridge glued on the drive to enable connection to SATA controllers.
Jeff
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