Hi,
On 13-12-17 17:22, Johannes Stezenbach wrote:
Hi,
On Wed, Dec 13, 2017 at 05:04:34PM +0100, Hans de Goede wrote:
On 13-12-17 16:25, Michael Turquette wrote:
On Wed, Dec 13, 2017 at 12:53 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
Although, maybe we need to have a specialized (derived)
ahci driver for these Atom SoCs and in there if no
disk is detected do this through the clock framework?
Yes please. x86 is already modeling some clocks properly through the
clock framework. During late init we clean up any clocks that were
enabled out of reset or by the firmware/bootloader but not claimed and
enabled by any Linux driver. That should ideally disable this
particular clock for the case when no SATA drive is present, and
require no quirk logic in the driver.
Ah so you're thinking a special ahci driver which knows about
the clock, yes I think that could work.
Or maybe do a match on the CPU model and if it is know to
not have SATA (or not routed to the outside), disable
the clock? That seems better because if I understood Johannes
correctly there is no SATA/AHCI PCI device (so nothing for
a driver to bind to) but the clock is still enabled, although
in that case the clock framework should do the right thing
if we revert commit d31fd43c0f9a "clk: x86: Do not gate clocks enabled by the firmware"
Please don't get confused with the other thread about clocks.
This issue sets the "disable IP" bit, found by doing stupid
experiments to enable S0ix on E200HA.
Ah my bad.
1. no idea if Cherry Trail even has SATA IP, maybe this is a
meaningless bit but PMC firmware carried over from
Bay Trail looks at it
There are no CHT SoCs with SATA AFAIK, but Braswell SoCs,
which I believe is the same die do have SATA.
I think the best fix here is to look at the model-string part
of the CPU-id and do a quirk based on that, setting the "disable IP"
bit for the SATA on all SoC models known to not have SATA
(Z8300, Z8350, Z8500, Z8550, Z8700, Z8750).
Rafael, Andy how does that sound as a solution?
2. BIOS should have set the bit, so it is a BIOS quirk
3. or maybe there is a much better solution that I don't know about
https://bugzilla.kernel.org/show_bug.cgi?id=193891
also has lspci output
Regards,
Hans
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
