On Thursday, January 05, 2017 04:20:29 PM Mika Westerberg wrote:
> On Thu, Jan 05, 2017 at 12:49:40PM +0200, Mika Westerberg wrote:
> > On Wed, Jan 04, 2017 at 10:58:10PM +0100, Rafael J. Wysocki wrote:
> > > I would rather add a quirk to the ACPI core to prevent the power resources in
> > > question from being enumerated. Or even to prevent ACPI PM from being
> > > used for the port in question.
> >
> > If we are going to add a quirk, I agree that it should be put to the
> > ACPI core.
> >
> > However, Windows seems to be able to use _PR3 just fine. So there is
> > something that we are missing or do not implement properly which causes
> > all the troubles. IMHO we should try to find out what that difference is
> > and fix that if possible.
>
> Here is one idea. The _OSC method is used as a handshake between OS and
> the BIOS to enable/disable certain features. One of those features is
> _PR3 support (ACPI specification 6.1 p.328):
>
> This bit is set if OSPM supports reading _PR3and using power
> resources to switch power. Note this handshake translates to an
> operating model that the platform and OSPM supports both the power
> model containing both D3hot and D3.
Ah, good catch!
I forgot about this one and we definitely should do this handshake.
> Some of our development platforms has BIOS option "RTD3 enable" which
> is used to enable/disable this flag (among other things). The BIOS
> should return acked caps when _OSC returns but we never check those in
> Linux.
>
> Kilian, can you try the below patch and send back dmesg when the system
> has been booted? It should show if the BIOS acks _PR3 or not.
>
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index 95855cb9d6fb..463eb2d69271 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -345,8 +345,15 @@ static void acpi_bus_osc_support(void)
> capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_APEI_SUPPORT;
> if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle)))
> return;
> +
> + acpi_handle_info(handle, "Supported caps: 0x%08x\n", capbuf[1]);
> +
> if (ACPI_SUCCESS(acpi_run_osc(handle, &context))) {
> u32 *capbuf_ret = context.ret.pointer;
> +
> + acpi_handle_info(handle, "Acked caps: 0x%08x (_PR3: %s)\n", capbuf_ret[1],
> + capbuf_ret[1] & OSC_SB_PR3_SUPPORT ? "on" : "off");
> +
> if (context.ret.length > OSC_SUPPORT_DWORD) {
> osc_sb_apei_support_acked =
> capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_APEI_SUPPORT;
> --
Thanks,
Rafael
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