From: bugzilla-daemon@kernel.org
To: linux-bluetooth@vger.kernel.org
Subject: [Bug 222157] New: Macbook 8,1 Bluetooth Fix
Date: Tue, 20 Oct 2026 02:39:03 +0000 [thread overview]
Message-ID: <bug-222157-62941@https.bugzilla.kernel.org/> (raw)
https://bugzilla.kernel.org/show_bug.cgi?id=222157
Bug ID: 222157
Summary: Macbook 8,1 Bluetooth Fix
Product: Drivers
Version: 2.5
Hardware: Intel
OS: Linux
Status: NEW
Severity: normal
Priority: P3
Component: Bluetooth
Assignee: linux-bluetooth@vger.kernel.org
Reporter: zach.robinson2e@gmail.com
Regression: No
Created attachment 311195
--> https://bugzilla.kernel.org/attachment.cgi?id=311195&action=edit
macbook8-1-bluetooth-linux fix
Built-in Bluetooth working on MacBook8,1 (Ubuntu 26.04, kernel 7.0.0-38):
BCM4350C0 via hci_uart_bcm at 3 Mbaud. Four stacked issues:
1. DSDT: URT0 has two children, SSDC (apple-uart-ssdc) and BLTH (BCM2E7C).
serdev attaches SSDC first, so BLTH fails with -EBUSY. Workaround: remove
SSDC via a DSDT override (the mux Lukas Wunner described in 2017).
2. LPSS UART (8086:9ce3, 8250_lpss) using DMA from dw_dmac_pci (8086:9ce0):
TX never completes (tx:0 in /proc/tty/driver/serial). Blacklisting
dw_dmac_pci forces PIO and TX works.
3. BTLP(0) only sets GD54 as input, leaving the BT_WAKE line floating; the
chip stays asleep with CTS low. Workaround: make BTLP a no-op.
4. The chip needs ~3 s after BTPU before it answers reliably (it emits a
~167 KB burst ~2 s after power-on). Workaround: Sleep(4000) in BTPU.
The UART mux (GPIO 36) already defaults to Bluetooth, and the 3 Mbaud from
_DSM is correct. Full write-up with the DSDT patch steps attached.
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