Bluetooth: hci_bcm: Default to 4 Mbps

[PATCH] Bluetooth: hci_bcm: Default to 4 Mbps

Posted by Paul Cercueil 4 weeks ago

The ACPI path already did default to 4000000 baud, while the OF path did
not, for some reason. This meant that unless overridden with the
'max-speed' OF property, the serial port would stay at the init speed of
115200 bps, making it unsuitable with high-speed Bluetooth devices like
audio equipment.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/bluetooth/hci_bcm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/bluetooth/hci_bcm.c b/drivers/bluetooth/hci_bcm.c
index 9a103db7e355..c44d552f9ad5 100644
--- a/drivers/bluetooth/hci_bcm.c
+++ b/drivers/bluetooth/hci_bcm.c
@@ -1224,6 +1224,7 @@ static int bcm_acpi_probe(struct bcm_device *dev)
 
 static int bcm_of_probe(struct bcm_device *bdev)
 {
+	bdev->oper_speed = 4000000;
 	bdev->use_autobaud_mode = device_property_read_bool(bdev->dev,
 							    "brcm,requires-autobaud-mode");
 	device_property_read_u32(bdev->dev, "max-speed", &bdev->oper_speed);
-- 
2.53.0

Re: [PATCH] Bluetooth: hci_bcm: Default to 4 Mbps

Posted by Luiz Augusto von Dentz 3 weeks, 5 days ago

Hi Paul,

On Sat, Aug 29, 2026 at 6:02 AM Paul Cercueil <paul@crapouillou.net> wrote:
>
> The ACPI path already did default to 4000000 baud, while the OF path did
> not, for some reason. This meant that unless overridden with the
> 'max-speed' OF property, the serial port would stay at the init speed of
> 115200 bps, making it unsuitable with high-speed Bluetooth devices like
> audio equipment.
>
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  drivers/bluetooth/hci_bcm.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/bluetooth/hci_bcm.c b/drivers/bluetooth/hci_bcm.c
> index 9a103db7e355..c44d552f9ad5 100644
> --- a/drivers/bluetooth/hci_bcm.c
> +++ b/drivers/bluetooth/hci_bcm.c
> @@ -1224,6 +1224,7 @@ static int bcm_acpi_probe(struct bcm_device *dev)
>
>  static int bcm_of_probe(struct bcm_device *bdev)
>  {
> +       bdev->oper_speed = 4000000;
>         bdev->use_autobaud_mode = device_property_read_bool(bdev->dev,
>                                                             "brcm,requires-autobaud-mode");
>         device_property_read_u32(bdev->dev, "max-speed", &bdev->oper_speed);
> --
> 2.53.0

Sashiko flagged a problem with this:

https://sashiko.dev/#/patchset/20260829100205.113655-1-paul%40crapouillou.net

-- 
Luiz Augusto von Dentz

Re: [PATCH] Bluetooth: hci_bcm: Default to 4 Mbps

Posted by Paul Cercueil 3 weeks, 4 days ago

Hi Luiz,

Le lundi 31 août 2026 à 10:56 -0400, Luiz Augusto von Dentz a écrit :
> Hi Paul,
> 
> On Sat, Aug 29, 2026 at 6:02 AM Paul Cercueil <paul@crapouillou.net>
> wrote:
> > 
> > The ACPI path already did default to 4000000 baud, while the OF
> > path did
> > not, for some reason. This meant that unless overridden with the
> > 'max-speed' OF property, the serial port would stay at the init
> > speed of
> > 115200 bps, making it unsuitable with high-speed Bluetooth devices
> > like
> > audio equipment.
> > 
> > Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> > ---
> >  drivers/bluetooth/hci_bcm.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/bluetooth/hci_bcm.c
> > b/drivers/bluetooth/hci_bcm.c
> > index 9a103db7e355..c44d552f9ad5 100644
> > --- a/drivers/bluetooth/hci_bcm.c
> > +++ b/drivers/bluetooth/hci_bcm.c
> > @@ -1224,6 +1224,7 @@ static int bcm_acpi_probe(struct bcm_device
> > *dev)
> > 
> >  static int bcm_of_probe(struct bcm_device *bdev)
> >  {
> > +       bdev->oper_speed = 4000000;
> >         bdev->use_autobaud_mode = device_property_read_bool(bdev-
> > >dev,
> >                                                            
> > "brcm,requires-autobaud-mode");
> >         device_property_read_u32(bdev->dev, "max-speed", &bdev-
> > >oper_speed);
> > --
> > 2.53.0
> 
> Sashiko flagged a problem with this:
> 
> https://sashiko.dev/#/patchset/20260829100205.113655-1-paul%40crapouillou.net

Noted.

The argument about breaking Devicetree backwards compatibility is a
good point, I didn't think about that.

Disregard this patch then.

Cheers,
-Paul