Re: [PATCH v2] ahci: implement aggressive SATA device sleep support

On Mon, Aug 27, 2012 at 6:36 AM, Huang, Shane [off-list ref] wrote:

quoted

To avoid attempting to enable on older devices, you will need an
appropriate test (ata_id_has_ncq perhaps?)

So far I don't find better method to exclude old devices than yours.

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As you figured out in the other email, I was referring to sata_settings

I'm going to modify both sata_settings and ID[78].

Sounds good.

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I just do not like programming the device, when power policy may
indicate otherwise.

Most conservative is to leave devslp feature in reset state and not
touch device or host until power policy dictates it is time to program
host + device.

OK, I'll move setting feature back to ahci_set_aggressive_devslp().
I'm trying to avoid setting feature each time for every sleep to
improve performance.

Adding pp->device_devslp_enabled with the code below does not make
much difference because it is still called for every sleep.
Do you have good suggestion?

Any should we also call setting feature to disable device DevSlp
for each !sleep?

Well we want to issue the ATA command to the device at each -power
policy- transition, not for each aggressive sleep.

     Jeff