On Monday, January 7, 2019 2:45:14 PM CET Rafael J. Wysocki wrote:
> On Monday, January 7, 2019 1:43:29 PM CET Rafael J. Wysocki wrote:
> > On Mon, Jan 7, 2019 at 12:51 PM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
> > >
> > > ca On Sat, Jan 5, 2019 at 2:17 PM Zhang Rui <rui.zhang@xxxxxxxxx> wrote:
> > > >
> > > > From 6f2fac0ffcd7fd61036baa0798ab171496cff50f Mon Sep 17 00:00:00 2001
> > > > From: Zhang Rui <rui.zhang@xxxxxxxxx>
> > > > Date: Fri, 4 Jan 2019 14:35:52 +0800
> > > > Subject: [PATCH] ACPI/ACPICA: Run EC _REG explicitly for ECDT
> > > >
> > > > commit d737f333b211 ("ACPI: probe ECDT before loading AML tables
> > > > regardless of module-level code flag") probes ECDT before loading
> > > > the AML tables.
> > > >
> > > > This is the right thing to do according to the ACPI Spec, but
> > > > unfortunately, it breaks the current kernel EC/ECDT support, and makes
> > > > many devices, including battery, lid, etc, fails to work on a variety
> > > > of platforms.
> > > >
> > > > This is because:
> > > > 1. Probing ECDT requires installing EC address space handler
> > > > 2. EC _REG can not be evaluated at the time when probing ECDT because AML
> > > > tables have not been loaded yet.
> > > > 3. Many devices fail to work because EC _REG is not evaluated.
> > > >
> > > > To fix this, a solution is proposed in this patch to evaluate EC _REG
> > > > explicitly in ACPICA, if ECDT has been probed.
> > >
> > > It would be good to give some more details here as the patch itself
> > > appears to be rather convoluted.
> > >
> > > Also, the description above doesn't actually explain why the problem
> > > is there, as it doesn't explain why probing the ECDT early causes the
> > > EC _REG to be not evaluated.
> > >
> > > It looks like the failure is due to the change of the ordering between
> > > acpi_load_tables() and acpi_ec_ecdt_probe() in the
> > > acpi_gbl_group_module_level_code case which causes the EC to be probed
> > > before instantiating the namespace and _REG obviously cannot be
> > > evaluated then.
> >
> > So what happens is:
> >
> > acpi_ec_ecdt_probe()
> > acpi_ec_ecdt_probe()
> > acpi_config_boot_ec(ec, ACPI_ROOT_OBJECT, false, true)
> > ...
> > ec->handle = ACPI_ROOT_OBJECT;
> > ...
> > acpi_ec_setup(ec, false)
> > ec_install_handlers(ec, false)
> >
> > acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
> > ACPI_ADR_SPACE_EC, &acpi_ec_space_handler, NULL, ec)
> > ...
> > set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)
> >
> > and now it returns, because handle_events is "false".
> >
> > Next time acpi_ec_setup() is called from acpi_ec_add() that can be
> > invoked in two ways, either through
> > acpi_bus_register_driver(&acpi_ec_driver) which runs it for the DSDT
> > EC (if found), or through acpi_ec_ecdt_start() and
> > acpi_bus_register_early_device().
> >
> > There are two cases in there, the acpi_config_boot_ec() one and the
> > direct invocation of acpi_ec_setup() when acpi_is_boot_ec(ec) returns
> > "false". The former is the failing case AFAICS, because
> > acpi_ec_ecdt_probe() (if successful) has set boot_ec as well as
> > ec->command_addr and ec->data_addr.
> >
> > So acpi_config_boot_ec() runs again and since boot_ec->handle has not
> > been updated, it doesn't call ec_remove_handlers(), and because the
> > EC_FLAGS_EC_HANDLER_INSTALLED is set, the address space handler
> > installed previously is retained and _REG is not evaluated. Since it
> > wasn't evaluated before (as it was not present then), it is never
> > evaluated and the failure occurs.
> >
> > So it looks like clearing ec-> handle before invoking
> > acpi_config_boot_ec() in the is_ecdt case in acpi_ec_add() can help,
> > can't it?
>
> Well, that wouldn't work, because ec->handle is checked by acpi_config_boot_ec()
> too. What might work would be to clear it and then pass the original to
> acpi_config_boot_ec() as 'handle'. Anyway, the patch below should cover
> all of the different cases just fine, so can you try this one, please?
>
> ---
> drivers/acpi/ec.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> Index: linux-pm/drivers/acpi/ec.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/ec.c
> +++ linux-pm/drivers/acpi/ec.c
> @@ -1545,12 +1545,13 @@ static int acpi_config_boot_ec(struct ac
> int ret;
>
> /*
> - * Changing the ACPI handle results in a re-configuration of the
> - * boot EC. And if it happens after the namespace initialization,
> - * it causes _REG evaluations.
> + * It is necessary to evaluate the _REG method for the EC address space
> + * handler, but it might not be evaluated when installing that handler
> + * previously (as that might happen when the namespace was not present
> + * yet), so remove the handler at this point to force the evaluation of
> + * _REG when it is installed again by acpi_ec_setup() below.
> */
> - if (boot_ec && boot_ec->handle != handle)
> - ec_remove_handlers(boot_ec);
> + ec_remove_handlers(ec);
>
> /* Unset old boot EC */
> if (boot_ec != ec)
On a second thought, this may cause _REG to be executed twice in a row
for the EC address space (in the DSDT boot EC case), so it probably is
better to only remove the handler in the "ECDT EC" case:
---
drivers/acpi/ec.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
Index: linux-pm/drivers/acpi/ec.c
===================================================================
--- linux-pm.orig/drivers/acpi/ec.c
+++ linux-pm/drivers/acpi/ec.c
@@ -1637,7 +1637,18 @@ static int acpi_ec_add(struct acpi_devic
if (acpi_is_boot_ec(ec)) {
boot_ec_is_ecdt = is_ecdt;
- if (!is_ecdt) {
+ if (is_ecdt) {
+ /*
+ * It is necessary to evaluate the _REG method for the
+ * EC address space handler, but it was not evaluated
+ * when installing that handler previously (as that
+ * happened when the namespace was not present yet), so
+ * remove the handler at this point to force the
+ * evaluation of _REG when it is installed again by
+ * acpi_config_boot_ec() below.
+ */
+ ec_remove_handlers(ec);
+ } else {
/*
* Trust PNP0C09 namespace location rather than
* ECDT ID. But trust ECDT GPE rather than _GPE
