[PATCH v5 2/2] btbcm: disable read tx power for affected Macs with the T2 Security chip

From: Aditya Garg
Date: Mon Nov 29 2021 - 04:28:28 EST


From: Aditya Garg <gargaditya08@xxxxxxxx>

Some Macs with the T2 security chip had Bluetooth not working.
To fix it we add DMI based quirks to disable querying of LE Tx power.

Signed-off-by: Aditya Garg <gargaditya08@xxxxxxxx>
Reported-by: Orlando Chamberlain <redecorating@xxxxxxxxxxxxxx>
Link:
https://lore.kernel.org/r/4970a940-211b-25d6-edab-21a815313954@xxxxxxxxxxxxxx
Fixes: 7c395ea521e6 ("Bluetooth: Query LE tx power on startup")
---
drivers/bluetooth/btbcm.c | 40 +++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)

diff --git a/drivers/bluetooth/btbcm.c b/drivers/bluetooth/btbcm.c
index e4182acee488c5..40f7c9c5cf0a5a 100644
--- a/drivers/bluetooth/btbcm.c
+++ b/drivers/bluetooth/btbcm.c
@@ -8,6 +8,7 @@

#include <linux/module.h>
#include <linux/firmware.h>
+#include <linux/dmi.h>
#include <asm/unaligned.h>

#include <net/bluetooth/bluetooth.h>
@@ -343,9 +344,44 @@ static struct sk_buff *btbcm_read_usb_product(struct hci_dev *hdev)
return skb;
}

+static const struct dmi_system_id disable_broken_read_transmit_power[] = {
+ {
+ .matches = {
+ DMI_MATCH(DMI_BOARD_VENDOR, "Apple Inc."),
+ DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro16,1"),
+ },
+ },
+ {
+ .matches = {
+ DMI_MATCH(DMI_BOARD_VENDOR, "Apple Inc."),
+ DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro16,2"),
+ },
+ },
+ {
+ .matches = {
+ DMI_MATCH(DMI_BOARD_VENDOR, "Apple Inc."),
+ DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro16,4"),
+ },
+ },
+ {
+ .matches = {
+ DMI_MATCH(DMI_BOARD_VENDOR, "Apple Inc."),
+ DMI_MATCH(DMI_PRODUCT_NAME, "iMac20,1"),
+ },
+ },
+ {
+ .matches = {
+ DMI_MATCH(DMI_BOARD_VENDOR, "Apple Inc."),
+ DMI_MATCH(DMI_PRODUCT_NAME, "iMac20,2"),
+ },
+ },
+ { }
+};
+
static int btbcm_read_info(struct hci_dev *hdev)
{
struct sk_buff *skb;
+ const struct dmi_system_id *dmi_id;

/* Read Verbose Config Version Info */
skb = btbcm_read_verbose_config(hdev);
@@ -363,6 +399,10 @@ static int btbcm_read_info(struct hci_dev *hdev)
bt_dev_info(hdev, "BCM: features 0x%2.2x", skb->data[1]);
kfree_skb(skb);

+ /* Read DMI and disable broken Read LE Min/Max Tx Power */
+ if (dmi_first_match(disable_broken_read_transmit_power))
+ set_bit(HCI_QUIRK_BROKEN_READ_TRANSMIT_POWER, &hdev->quirks);
+
return 0;
}