[Bug 222157] New: Macbook 8,1 Bluetooth Fix

[Bug 222157] New: Macbook 8,1 Bluetooth Fix

[bugzilla-daemon]

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.

-- 
You may reply to this email to add a comment.

You are receiving this mail because:
You are the assignee for the bug.