ACPI / EC: Fix a boot EC regresion by restoring boot EC support for the DSDT EC

According to the Windows probing result, during the table loading, the EC
device described in the ECDT should be used. And the ECDT EC is also
effective during the period the namespace objects are initialized (we can
see a separate process executing _STA/_INI on Windows before executing
other device specific control methods, for example, EC._REG). During the
device enumration, the EC device described in the DSDT should be used. But
there are differences between Linux and Windows around the device probing
order. Thus in Linux, we should enable the DSDT EC as early as possible
before enumerating devices in order not to trigger issues related to the
device enumeration order differences.

This patch thus converts acpi_boot_ec_enable() into acpi_ec_dsdt_probe() to
fix the gap. This also fixes a user reported regression triggered after we
switched the "table loading"/"ECDT support" to be ACPI spec 2.0 compliant.

Fixes: 59f0aa9480cf (ACPI 2.0 / ECDT: Remove early namespace reference from EC)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=119261
Reported-and-tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 31e8da648fffb9b6db10cda340bcc394f3a95994..262ca31b86d9311c05bd840c7fb8bb0aa3b09b34 100644 (file)
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -1051,7 +1051,7 @@ static int __init acpi_bus_init(void)
         * Maybe EC region is required at bus_scan/acpi_get_devices. So it
         * is necessary to enable it as early as possible.
         */
-       acpi_boot_ec_enable();
+       acpi_ec_dsdt_probe();
 
        printk(KERN_INFO PREFIX "Interpreter enabled\n");
 

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 0e70181f150c9eae5e00b8f9a24a41382ee41bbc..73c76d646064700dc1bb51905b4dbc70b415aabf 100644 (file)
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -1446,10 +1446,30 @@ ec_parse_io_ports(struct acpi_resource *resource, void *context)
        return AE_OK;
 }
 
-int __init acpi_boot_ec_enable(void)
+static const struct acpi_device_id ec_device_ids[] = {
+       {"PNP0C09", 0},
+       {"", 0},
+};
+
+int __init acpi_ec_dsdt_probe(void)
 {
-       if (!boot_ec)
+       acpi_status status;
+
+       if (boot_ec)
                return 0;
+
+       /*
+        * Finding EC from DSDT if there is no ECDT EC available. When this
+        * function is invoked, ACPI tables have been fully loaded, we can
+        * walk namespace now.
+        */
+       boot_ec = make_acpi_ec();
+       if (!boot_ec)
+               return -ENOMEM;
+       status = acpi_get_devices(ec_device_ids[0].id,
+                                 ec_parse_device, boot_ec, NULL);
+       if (ACPI_FAILURE(status) || !boot_ec->handle)
+               return -ENODEV;
        if (!ec_install_handlers(boot_ec)) {
                first_ec = boot_ec;
                return 0;
@@ -1457,11 +1477,6 @@ int __init acpi_boot_ec_enable(void)
        return -EFAULT;
 }
 
-static const struct acpi_device_id ec_device_ids[] = {
-       {"PNP0C09", 0},
-       {"", 0},
-};
-
 #if 0
 /*
  * Some EC firmware variations refuses to respond QR_EC when SCI_EVT is not

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 7c188472d9c276f985f06f6c658e7329b7f2423b..b4733b56fed1b389261af4126596c6ec0516da0b 100644 (file)
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -180,7 +180,7 @@ typedef int (*acpi_ec_query_func) (void *data);
 
 int acpi_ec_init(void);
 int acpi_ec_ecdt_probe(void);
-int acpi_boot_ec_enable(void);
+int acpi_ec_dsdt_probe(void);
 void acpi_ec_block_transactions(void);
 void acpi_ec_unblock_transactions(void);
 void acpi_ec_unblock_transactions_early(void);