Subject: [PATCH v3 1/2] Bluetooth: Add new quirk for broken local ext features page 2

From: Bastian Germann <[email-masked]>
Date: Tue, 7 Feb 2023 00:39:10 +0100

From: Vasily Khoruzhick <[email-masked]>

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 <[email-masked]>
Signed-off-by: Bastian Germann <[email-masked]>
---
 include/net/bluetooth/hci.h | 7 +++++++
 net/bluetooth/hci_event.c   | 4 +++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index 8d773b042c85..7127313140cf 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..83ebc8e65b42 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -886,7 +886,9 @@ 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)
+	if (!test_bit(HCI_QUIRK_BROKEN_LOCAL_EXT_FEATURES_PAGE_2,
+		      &hdev->quirks) &&
+	    hdev->max_page < rp->max_page)
 		hdev->max_page = rp->max_page;
 
 	if (rp->page < HCI_MAX_PAGES)
-- 
2.39.1