Subject: [PATCH v2 1/3] Bluetooth: Add new quirk for broken local ext features max_page

From: Bastian Germann <[email-masked]>
Date: Tue, 24 May 2022 23:21:52 +0200

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]>
[rebase on current tree]
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 69ef31cea582..af26e8051905 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -265,6 +265,13 @@ enum {
 	 * runtime suspend, because event filtering takes place there.
 	 */
 	HCI_QUIRK_BROKEN_FILTER_CLEAR_ALL,
+
+	/* 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_FTR_MAX_PAGE,
 };
 
 /* HCI device flags */
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 66451661283c..52b358c33344 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -837,7 +837,9 @@ 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_FTR_MAX_PAGE,
+		      &hdev->quirks) &&
+	    hdev->max_page < rp->max_page)
 		hdev->max_page = rp->max_page;
 
 	if (rp->page < HCI_MAX_PAGES)
-- 
2.36.1