ARM: dts: sun8i-q8-common: enable bluetooth on SDIO Wi-Fi

2016?12?9? ??4:07? Maxime Ripard <[email protected]>???

Quoted 41 lines · Icenowy Zheng

Quoted 24 lines

Some SDIO Wi-Fi chips (such as RTL8703AS) have a UART bluetooth, which has a dedicated enable pin (PL8 in the reference design).

Enable the pin in the same way as the WLAN enable pins.

Tested on an A33 Q8 tablet with RTL8703AS.

Signed-off-by Icenowy Zheng <[email protected]>

---

This patch should be coupled with the uart1 node patch I send before:
http://lists.infradead.org/pipermail/linux-arm-kernel/2016-December/471997.html

For RTL8703AS, the rtl8723bs bluetooth code is used, which can be retrieve from:
https://github.com/lwfinger/rtl8723bs_bt

? arch/arm/boot/dts/sun8i-q8-common.dtsi | 2 +-
? 1 file changed, 1 insertion(+), 1 deletion(-)

arch/arm/boot/dts/sun8i-q8-common.dtsi +0 -0

index c676940..4aeb5bb 100644 
@@ -88,7 +88,7 @@ 

Quoted 8 lines

?
? &r_pio {
? wifi_pwrseq_pin_q8: wifi_pwrseq_pin at 0 {
- pins = "PL6", "PL7", "PL11";
+ pins = "PL6", "PL7", "PL8", "PL11";
? function = "gpio_in";
? bias-pull-up;
? };

There's several things wrong here. The first one is that you rely solely on the pinctrl state to maintain a reset line. This is very fragile (especially since the GPIO pinctrl state are likely to go away at some point), but it also means that if your driver wants to recover from that situation at some point, it won't work.

Quoted 4 lines

The other one is that the bluetooth and wifi chips are two devices in linux, and you assign that pin to the wrong device (wifi).

rfkill-gpio is made just for that, so please use it.

The GPIO is not for the radio, but for the full Bluetooth part.

If it's set to 0, then the bluetooth part will reset, and the hciattach will fail.

The BSP uses this as a rfkill, and the result is that the bluetooth on/off switch do not work properly.

Quoted 47 lines

?2016?12?9? ??4:07? Maxime Ripard <[email protected]>???
?>
?> On Tue, Dec 06, 2016 at 04:08:38PM +0800, Icenowy Zheng wrote:
?> > Some SDIO Wi-Fi chips (such as RTL8703AS) have a UART bluetooth, which
?> > has a dedicated enable pin (PL8 in the reference design).
?> >
?> > Enable the pin in the same way as the WLAN enable pins.
?> >
?> > Tested on an A33 Q8 tablet with RTL8703AS.
?> >
?> > Signed-off-by: Icenowy Zheng <[email protected]>
?> > ---
?> >
?> > This patch should be coupled with the uart1 node patch I send before:
?> > http://lists.infradead.org/pipermail/linux-arm-kernel/2016-December/471997.html
?> >
?> > For RTL8703AS, the rtl8723bs bluetooth code is used, which can be retrieve from:
?> > https://github.com/lwfinger/rtl8723bs_bt
?> >
?> >? arch/arm/boot/dts/sun8i-q8-common.dtsi | 2 +-
?> >? 1 file changed, 1 insertion(+), 1 deletion(-)
?> >
?> > diff --git a/arch/arm/boot/dts/sun8i-q8-common.dtsi b/arch/arm/boot/dts/sun8i-q8-common.dtsi ?> > index c676940..4aeb5bb 100644
?> > --- a/arch/arm/boot/dts/sun8i-q8-common.dtsi
?> > +++ b/arch/arm/boot/dts/sun8i-q8-common.dtsi
?> > @@ -88,7 +88,7 @@
?> >
?> >? &r_pio {
?> >? wifi_pwrseq_pin_q8: wifi_pwrseq_pin at 0 {
?> > - pins = "PL6", "PL7", "PL11";
?> > + pins = "PL6", "PL7", "PL8", "PL11";
?> >? function = "gpio_in";
?> >? bias-pull-up;
?> >? };
?>
?> There's several things wrong here. The first one is that you rely
?> solely on the pinctrl state to maintain a reset line. This is very
?> fragile (especially since the GPIO pinctrl state are likely to go away
?> at some point), but it also means that if your driver wants to recover
?> from that situation at some point, it won't work.
?>
?> The other one is that the bluetooth and wifi chips are two devices in
?> linux, and you assign that pin to the wrong device (wifi).
?>
?> rfkill-gpio is made just for that, so please use it.

Quoted 1 line

?The GPIO is not for the radio, but for the full Bluetooth part.

I know.

Quoted 2 lines

?If it's set to 0, then the bluetooth part will reset, and the ?hciattach will fail.

Both rfkill-gpio and rfkill-regulator will shutdown when called (either by poking the reset pin or shutting down the regulator), so that definitely seems like an expected behavior to put the device in reset.

Quoted 2 lines

?The BSP uses this as a rfkill, and the result is that the bluetooth ?on/off switch do not work properly.

Then rfkill needs fixing, but working around it by hoping that the core will probe an entirely different device, and enforcing a default that the rest of the kernel might or might not change is both fragile and wrong.

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

Quoted 31 lines

Quoted 19 lines

?> >? &r_pio {
?> >? wifi_pwrseq_pin_q8: wifi_pwrseq_pin at 0 {
?> > - pins = "PL6", "PL7", "PL11";
?> > + pins = "PL6", "PL7", "PL8", "PL11";
?> >? function = "gpio_in";
?> >? bias-pull-up;
?> >? };
?>
?> There's several things wrong here. The first one is that you rely ?> solely on the pinctrl state to maintain a reset line. This is very ?> fragile (especially since the GPIO pinctrl state are likely to go away ?> at some point), but it also means that if your driver wants to recover ?> from that situation at some point, it won't work.
?>
?> The other one is that the bluetooth and wifi chips are two devices in ?> linux, and you assign that pin to the wrong device (wifi). ?>
?> rfkill-gpio is made just for that, so please use it.

Quoted 1 line

?The GPIO is not for the radio, but for the full Bluetooth part.

I know.

Quoted 2 lines

?If it's set to 0, then the bluetooth part will reset, and the ?hciattach will fail.

Both rfkill-gpio and rfkill-regulator will shutdown when called (either by poking the reset pin or shutting down the regulator), so that definitely seems like an expected behavior to put the device in reset.

Quoted 7 lines

Quoted 2 lines

?The BSP uses this as a rfkill, and the result is that the bluetooth ?on/off switch do not work properly.

Then rfkill needs fixing, but working around it by hoping that the core will probe an entirely different device, and enforcing a default that the rest of the kernel might or might not change is both fragile and wrong.

I think a rfkill-gpio here works just like the BSP rfkill...

The real problem is that the Realtek UART bluetooth driver is a userspace program (a modified hciattach), which is not capable of the GPIO reset...

Quoted 39 lines

?>> ?> >? &r_pio {
?>> ?> >? wifi_pwrseq_pin_q8: wifi_pwrseq_pin at 0 {
?>> ?> > - pins = "PL6", "PL7", "PL11";
?>> ?> > + pins = "PL6", "PL7", "PL8", "PL11";
?>> ?> >? function = "gpio_in";
?>> ?> >? bias-pull-up;
?>> ?> >? };
?>> ?>
?>> ?> There's several things wrong here. The first one is that you rely ?>> ?> solely on the pinctrl state to maintain a reset line. This is very ?>> ?> fragile (especially since the GPIO pinctrl state are likely to go away ?>> ?> at some point), but it also means that if your driver wants to recover ?>> ?> from that situation at some point, it won't work.
?>> ?>
?>> ?> The other one is that the bluetooth and wifi chips are two devices in ?>> ?> linux, and you assign that pin to the wrong device (wifi). ?>> ?>
?>> ?> rfkill-gpio is made just for that, so please use it.
?>>
?>> ?The GPIO is not for the radio, but for the full Bluetooth part. ?>
?> I know.
?>
?>> ?If it's set to 0, then the bluetooth part will reset, and the ?>> ?hciattach will fail.
?>
?> Both rfkill-gpio and rfkill-regulator will shutdown when called ?> (either by poking the reset pin or shutting down the regulator), so ?> that definitely seems like an expected behavior to put the device in ?> reset.
?>
?>> ?The BSP uses this as a rfkill, and the result is that the bluetooth ?>> ?on/off switch do not work properly.
?>
?> Then rfkill needs fixing, but working around it by hoping that the ?> core will probe an entirely different device, and enforcing a default ?> that the rest of the kernel might or might not change is both fragile ?> and wrong.

Quoted 4 lines

?I think a rfkill-gpio here works just like the BSP rfkill...

?The real problem is that the Realtek UART bluetooth driver is a userspace ?program (a modified hciattach), which is not capable of the GPIO reset...

Can't you run rfkill before attaching? What is the problem exactly? It's not in reset for long enough?

This seems more and more like an issue in the BT stack you're using. We might consider workarounds in the kernel, but they have to be correct.

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

19.12.2016, 18:09, "Maxime Ripard" <[email protected]>:

Quoted 45 lines · Icenowy Zheng

Quoted 39 lines

Quoted 31 lines

Quoted 14 lines

Quoted 14 lines

Quoted 7 lines

&r_pio {
wifi_pwrseq_pin_q8: wifi_pwrseq_pin at 0 {
- pins = "PL6", "PL7", "PL11";
+ pins = "PL6", "PL7", "PL8", "PL11";
function = "gpio_in";
bias-pull-up;
};

There's several things wrong here. The first one is that you rely solely on the pinctrl state to maintain a reset line. This is very fragile (especially since the GPIO pinctrl state are likely to go away at some point), but it also means that if your driver wants to recover from that situation at some point, it won't work.

Quoted 6 lines

Quoted 4 lines

The other one is that the bluetooth and wifi chips are two devices in linux, and you assign that pin to the wrong device (wifi).

rfkill-gpio is made just for that, so please use it.

The GPIO is not for the radio, but for the full Bluetooth part.

I know.

Quoted 2 lines

If it's set to 0, then the bluetooth part will reset, and the hciattach will fail.

Both rfkill-gpio and rfkill-regulator will shutdown when called (either by poking the reset pin or shutting down the regulator), so that definitely seems like an expected behavior to put the device in reset.

Quoted 7 lines

Quoted 2 lines

The BSP uses this as a rfkill, and the result is that the bluetooth on/off switch do not work properly.

Then rfkill needs fixing, but working around it by hoping that the core will probe an entirely different device, and enforcing a default that the rest of the kernel might or might not change is both fragile and wrong.

Quoted 4 lines

I think a rfkill-gpio here works just like the BSP rfkill...

The real problem is that the Realtek UART bluetooth driver is a userspace program (a modified hciattach), which is not capable of the GPIO reset...

Quoted 6 lines

Can't you run rfkill before attaching? What is the problem exactly? It's not in reset for long enough?

This seems more and more like an issue in the BT stack you're using. We might consider workarounds in the kernel, but they have to be correct.

One more rfkill interface will be generated for hci0 after hciattach, which can be safely toggled block and unblock.

However, if the GPIO is toggled down, the hciattach program will die.

The bluetooth stack I used is fd.o's BlueZ.

Quoted 8 lines

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

Quoted 55 lines · Icenowy Zheng

19.12.2016, 18:09, "Maxime Ripard" <[email protected]>:

Quoted 45 lines · Icenowy Zheng

Quoted 39 lines

Quoted 31 lines

Quoted 14 lines

Quoted 14 lines

Quoted 7 lines

&r_pio {
wifi_pwrseq_pin_q8: wifi_pwrseq_pin at 0 {
- pins = "PL6", "PL7", "PL11";
+ pins = "PL6", "PL7", "PL8", "PL11";
function = "gpio_in";
bias-pull-up;
};

There's several things wrong here. The first one is that you rely solely on the pinctrl state to maintain a reset line. This is very fragile (especially since the GPIO pinctrl state are likely to go away at some point), but it also means that if your driver wants to recover from that situation at some point, it won't work.

Quoted 6 lines

Quoted 4 lines

The other one is that the bluetooth and wifi chips are two devices in linux, and you assign that pin to the wrong device (wifi).

rfkill-gpio is made just for that, so please use it.

The GPIO is not for the radio, but for the full Bluetooth part.

I know.

Quoted 2 lines

If it's set to 0, then the bluetooth part will reset, and the hciattach will fail.

Both rfkill-gpio and rfkill-regulator will shutdown when called (either by poking the reset pin or shutting down the regulator), so that definitely seems like an expected behavior to put the device in reset.

Quoted 7 lines

Quoted 2 lines

The BSP uses this as a rfkill, and the result is that the bluetooth on/off switch do not work properly.

Then rfkill needs fixing, but working around it by hoping that the core will probe an entirely different device, and enforcing a default that the rest of the kernel might or might not change is both fragile and wrong.

Quoted 4 lines

I think a rfkill-gpio here works just like the BSP rfkill...

The real problem is that the Realtek UART bluetooth driver is a userspace program (a modified hciattach), which is not capable of the GPIO reset...

Quoted 6 lines

Can't you run rfkill before attaching? What is the problem exactly? It's not in reset for long enough?

This seems more and more like an issue in the BT stack you're using. We might consider workarounds in the kernel, but they have to be correct.

Quoted 6 lines

One more rfkill interface will be generated for hci0 after hciattach, which can be safely toggled block and unblock.

However, if the GPIO is toggled down, the hciattach program will die.

The bluetooth stack I used is fd.o's BlueZ.

I think the bigger issue is that the tty/serial subsystem does not have power sequencing support. Here we're trying to use rfkill to do that, but that doesn't seem to be what it was intended for. It might work with standalone USB bluetooth controllers that don't need any special setup, since the device will just appear and get registered. But it might not work so well with UART based adapters that need userspace fiddling with firmware and hciattach.