[PATCH v6 1/2] Bluetooth: Add new quirk for broken local ext features page 2

[Bastian Germann <bage@debian.org>]

From: Vasily Khoruzhick <anarsoul@gmail.com>

Some adapters (e.g. RTL8723CS) advertise that they have more than
2 pages for local ext features, but they don't support any features
declared in these pages. RTL8723CS reports max_page = 2 and declares
support for sync train and secure connection, but it responds with
either garbage or with error in status on corresponding commands.

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Bastian Germann <bage@debian.org>
---
 include/net/bluetooth/hci.h | 7 +++++++
 net/bluetooth/hci_event.c   | 9 +++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index 400f8a7d0c3f..997107bfc0b1 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -294,6 +294,13 @@ enum {
 	 * during the hdev->setup vendor callback.
 	 */
 	HCI_QUIRK_BROKEN_MWS_TRANSPORT_CONFIG,
+
+	/* When this quirk is set, max_page for local extended features
+	 * is set to 1, even if controller reports higher number. Some
+	 * controllers (e.g. RTL8723CS) report more pages, but they
+	 * don't actually support features declared there.
+	 */
+	HCI_QUIRK_BROKEN_LOCAL_EXT_FEATURES_PAGE_2,
 };
 
 /* HCI device flags */
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index ad92a4be5851..8d8547fa9032 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -886,8 +886,13 @@ static u8 hci_cc_read_local_ext_features(struct hci_dev *hdev, void *data,
 	if (rp->status)
 		return rp->status;
 
-	if (hdev->max_page < rp->max_page)
-		hdev->max_page = rp->max_page;
+	if (hdev->max_page < rp->max_page) {
+		if (test_bit(HCI_QUIRK_BROKEN_LOCAL_EXT_FEATURES_PAGE_2,
+			     &hdev->quirks))
+			bt_dev_warn(hdev, "broken local ext features page 2");
+		else
+			hdev->max_page = rp->max_page;
+	}
 
 	if (rp->page < HCI_MAX_PAGES)
 		memcpy(hdev->features[rp->page], rp->features, 8);
-- 
2.39.2