Hello, Matthew.
Matthew Garrett wrote:
On Wed, Mar 28, 2007 at 04:30:02PM +0900, Tejun Heo wrote:
Hi Tejun,
Firstly, could I ask you to take a look at the patch in
http://permalink.gmane.org/gmane.linux.acpi.devel/22066/ ? It deals with
some of these issues.
Yeap, I've seen the patch. That's why you're on the cc list in the
first place. :-)
ACPI support implementation in libata-dev supports both IDE and SATA
ACPI object layouts and subset of ATA ACPI methods - _SDD and _GTF.
It incorrectly uses ap->cbl (the port's cable type) to choose between
the two ACPI layouts. Association between the host and its ACPI
object is performed every time ACPI methods are invoked but the
association between an ATA device and its ACPI object is cached in
ata_device object.
These issues are both fixed in my patch, I believe.
Yeap, I think it's in the right direction but we need to go further.
* I'm not sure whether the complex walk libata-acpi is doing is justifiable.
* You'll end up doing _STM/_GTM on ahci controller on some BIOSen - 1.
it can be dangerous 2. you might get partial or incorrect mapping -
think about ICH8-split-to-two-PCI-fn-in-piix-mode case.
2-2. Missing proper _GTM/_STM support. As stated above, although -mm
contains _GTM/_STM support, it does not hook it to regular
exception handling path and thus _GTF cannot be used in a lot of
cases.
I've added _GTM and _STM support over suspend/resume. Right now they're
in the host power management code - I'm not sure whether they should be
here or the SCSI glue layer?
I think PM functions in libata-eh is better place and you also need to
do _GTF after _GTM during resume.
2-3. Misplaced _GTF hook. _GTF currently is called prior to every
device configuration. This is unnecessary and incorrect. The
ACPI spec specifies that _GTM/_STM and _GTF should be executed
during suspend/resume cycles not on every reset or
reconfiguration. This, for example, causes the following
problem.
That should be quite easily fixable with the above patch.
Yeap.
4-1. Depending on how questions in section 3 are answered, fix and
clean up ATA host/device <-> ACPI object association. Whether
IDE or SATA native style hierarchy is used should be determined
by driver flag not cable type. e.g. ahci and sata_sil24 should
use SATA native style hierarchy while ata_piix should use IDE
hierarchy whether the port is SATA or PATA.
I think this is just a matter of making sure that the sata and pata
handle matching code matches reality now :)
Currently 1/2 of libata-acpi code is dealing with the above. I'm trying
to figure out why it needs to be that complex.
Anyways, I think your patch is a step in the right direction, so
depending on how ACPI gurus enlighten us here, we can base further fix
on your patch. Let's see how the questions are answered.
Thanks.
--
tejun
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