2 files changed, 75 insertions, 26 deletions

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 3d304ff7f095..5f9b74b9b71f 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -126,6 +126,7 @@ static int EC_FLAGS_MSI; /* Out-of-spec MSI controller */
 static int EC_FLAGS_VALIDATE_ECDT; /* ASUStec ECDTs need to be validated */
 static int EC_FLAGS_SKIP_DSDT_SCAN; /* Not all BIOS survive early DSDT scan */
 static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */
+static int EC_FLAGS_QUERY_HANDSHAKE; /* Needs QR_EC issued when SCI_EVT set */
 
 /* --------------------------------------------------------------------------
  *                           Transaction Management
@@ -236,13 +237,8 @@ static bool advance_transaction(struct acpi_ec *ec)
                 }
                 return wakeup;
         } else {
-                /*
-                 * There is firmware refusing to respond QR_EC when SCI_EVT
-                 * is not set, for which case, we complete the QR_EC
-                 * without issuing it to the firmware.
-                 * https://bugzilla.kernel.org/show_bug.cgi?id=86211
-                 */
-                if (!(status & ACPI_EC_FLAG_SCI) &&
+                if (EC_FLAGS_QUERY_HANDSHAKE &&
+                    !(status & ACPI_EC_FLAG_SCI) &&
                     (t->command == ACPI_EC_COMMAND_QUERY)) {
                         t->flags |= ACPI_EC_COMMAND_POLL;
                         t->rdata[t->ri++] = 0x00;
@@ -334,13 +330,13 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
         pr_debug("***** Command(%s) started *****\n",
                  acpi_ec_cmd_string(t->command));
         start_transaction(ec);
-        spin_unlock_irqrestore(&ec->lock, tmp);
-        ret = ec_poll(ec);
-        spin_lock_irqsave(&ec->lock, tmp);
         if (ec->curr->command == ACPI_EC_COMMAND_QUERY) {
                 clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
                 pr_debug("***** Event stopped *****\n");
         }
+        spin_unlock_irqrestore(&ec->lock, tmp);
+        ret = ec_poll(ec);
+        spin_lock_irqsave(&ec->lock, tmp);
         pr_debug("***** Command(%s) stopped *****\n",
                  acpi_ec_cmd_string(t->command));
         ec->curr = NULL;
@@ -1012,6 +1008,18 @@ static int ec_enlarge_storm_threshold(const struct dmi_system_id *id)
 }
 
 /*
+ * Acer EC firmware refuses to respond QR_EC when SCI_EVT is not set, for
+ * which case, we complete the QR_EC without issuing it to the firmware.
+ * https://bugzilla.kernel.org/show_bug.cgi?id=86211
+ */
+static int ec_flag_query_handshake(const struct dmi_system_id *id)
+{
+        pr_debug("Detected the EC firmware requiring QR_EC issued when SCI_EVT set\n");
+        EC_FLAGS_QUERY_HANDSHAKE = 1;
+        return 0;
+}
+
+/*
  * On some hardware it is necessary to clear events accumulated by the EC during
  * sleep. These ECs stop reporting GPEs until they are manually polled, if too
  * many events are accumulated. (e.g. Samsung Series 5/9 notebooks)
@@ -1085,6 +1093,9 @@ static struct dmi_system_id ec_dmi_table[] __initdata = {
         {
         ec_clear_on_resume, "Samsung hardware", {
         DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD.")}, NULL},
+        {
+        ec_flag_query_handshake, "Acer hardware", {
+        DMI_MATCH(DMI_SYS_VENDOR, "Acer"), }, NULL},
         {},
 };
 
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index d670158a26c5..0476e90b2091 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -142,6 +142,53 @@ static int create_modalias(struct acpi_device *acpi_dev, char *modalias,
 }
 
 /*
+ * acpi_companion_match() - Can we match via ACPI companion device
+ * @dev: Device in question
+ *
+ * Check if the given device has an ACPI companion and if that companion has
+ * a valid list of PNP IDs, and if the device is the first (primary) physical
+ * device associated with it.
+ *
+ * If multiple physical devices are attached to a single ACPI companion, we need
+ * to be careful.  The usage scenario for this kind of relationship is that all
+ * of the physical devices in question use resources provided by the ACPI
+ * companion.  A typical case is an MFD device where all the sub-devices share
+ * the parent's ACPI companion.  In such cases we can only allow the primary
+ * (first) physical device to be matched with the help of the companion's PNP
+ * IDs.
+ *
+ * Additional physical devices sharing the ACPI companion can still use
+ * resources available from it but they will be matched normally using functions
+ * provided by their bus types (and analogously for their modalias).
+ */
+static bool acpi_companion_match(const struct device *dev)
+{
+        struct acpi_device *adev;
+        bool ret;
+
+        adev = ACPI_COMPANION(dev);
+        if (!adev)
+                return false;
+
+        if (list_empty(&adev->pnp.ids))
+                return false;
+
+        mutex_lock(&adev->physical_node_lock);
+        if (list_empty(&adev->physical_node_list)) {
+                ret = false;
+        } else {
+                const struct acpi_device_physical_node *node;
+
+                node = list_first_entry(&adev->physical_node_list,
+                                        struct acpi_device_physical_node, node);
+                ret = node->dev == dev;
+        }
+        mutex_unlock(&adev->physical_node_lock);
+
+        return ret;
+}
+
+/*
  * Creates uevent modalias field for ACPI enumerated devices.
  * Because the other buses does not support ACPI HIDs & CIDs.
  * e.g. for a device with hid:IBM0001 and cid:ACPI0001 you get:
@@ -149,20 +196,14 @@ static int create_modalias(struct acpi_device *acpi_dev, char *modalias,
  */
 int acpi_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env)
 {
-        struct acpi_device *acpi_dev;
         int len;
 
-        acpi_dev = ACPI_COMPANION(dev);
-        if (!acpi_dev)
-                return -ENODEV;
-
-        /* Fall back to bus specific way of modalias exporting */
-        if (list_empty(&acpi_dev->pnp.ids))
+        if (!acpi_companion_match(dev))
                 return -ENODEV;
 
         if (add_uevent_var(env, "MODALIAS="))
                 return -ENOMEM;
-        len = create_modalias(acpi_dev, &env->buf[env->buflen - 1],
+        len = create_modalias(ACPI_COMPANION(dev), &env->buf[env->buflen - 1],
                                 sizeof(env->buf) - env->buflen);
         if (len <= 0)
                 return len;
@@ -179,18 +220,12 @@ EXPORT_SYMBOL_GPL(acpi_device_uevent_modalias);
  */
 int acpi_device_modalias(struct device *dev, char *buf, int size)
 {
-        struct acpi_device *acpi_dev;
         int len;
 
-        acpi_dev = ACPI_COMPANION(dev);
-        if (!acpi_dev)
+        if (!acpi_companion_match(dev))
                 return -ENODEV;
 
-        /* Fall back to bus specific way of modalias exporting */
-        if (list_empty(&acpi_dev->pnp.ids))
-                return -ENODEV;
-
-        len = create_modalias(acpi_dev, buf, size -1);
+        len = create_modalias(ACPI_COMPANION(dev), buf, size -1);
         if (len <= 0)
                 return len;
         buf[len++] = '\n';
@@ -853,6 +888,9 @@ const struct acpi_device_id *acpi_match_device(const struct acpi_device_id *ids,
         if (!ids || !handle || acpi_bus_get_device(handle, &adev))
                 return NULL;
 
+        if (!acpi_companion_match(dev))
+                return NULL;
+
         return __acpi_match_device(adev, ids);
 }
 EXPORT_SYMBOL_GPL(acpi_match_device);