On 29-Nov-2021, at 7:30 PM, Aditya Garg [off-list ref] wrote:

From: Aditya Garg <redacted>

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 <redacted>
Reported-by: Orlando Chamberlain <redacted>
Link:
https://lore.kernel.org/r/4970a940-211b-25d6-edab-21a815313954@protonmail.com (local)
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;

	/* 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;
}