[PATCH 0/4] Bluetooth support for GXBB/GXL/GXM based devices

Kevin Hilman khilman at baylibre.com
Wed Jan 18 14:02:06 PST 2017

Martin Blumenstingl <martin.blumenstingl at googlemail.com> writes:

> Kevin,
> On Sun, Jan 15, 2017 at 11:32 PM, Martin Blumenstingl
> <martin.blumenstingl at googlemail.com> wrote:
>> This adds the missing kernel bits for Bluetooth support on the
>> Tronsmart Vega S95 (GXBB based) boards as well as for the GXL
>> P230/P231 and GXM Q200/Q201 reference boards.
>> The Bluetooth functionality on these boards is provided by the
>> SDIO wifi/Bluetooth combo-chip (Broadcom bcm43xx based). The
>> Bluetooth module on that combo-chip has to be taken out of reset,
>> which is taken care of the GPIO in the sdio_pwrseq.
>> Once the module is taken out of reset it can be set up from userspace
>> using the "hciattach" tool from bluez, which talks to the Bluetooth
>> module which is connected to one of the serial ports (in our case
>> uart_A). To get the Bluetooth module initialized within the timeout
>> defined by "hciattach" (and to achieve usable speeds for Bluetooth
>> transfers) the communication uses a speed of 2000000 baud, which was
>> not supported by meson_uart before.
>> NOTE: The .dts-changes from this series depends on my previous series
>> "add support for uart_AO_B" - see [0]
>> [0] http://lists.infradead.org/pipermail/linux-amlogic/2017-January/001982.html
>> Martin Blumenstingl (4):
>>   tty: serial: meson: allow baud-rates higher than 115200
>>   ARM64: dts: meson-gx: add the serial CTS and RTS pin groups
> Neil just informed me that Rob Herring is working on defining the UART
> Bluetooth device properly using devicetree (preparation for this is
> named "[PATCH v2 0/9] Serial slave device bus", see [0] for the
> mailing-list conversation and [1] for a WiP git repo).

Ah, good news.  I knew Rob had been talking about that for awhile, so
I'm glad to see it coming into existence.  Thanks for the pointers.

> This means that there will be a better solution than the one proposed
> in the meson-gx-p23x-q20x and meson-gxbb-vega-s95 patches (patches #1
> and #2 are not affected by this),> namely:
> - I'm currently (ab)using sdio-pwrseq node to power on the UART
> Bluetooth module, this can solved by specifying a bluetooth {  } node
> inside the &uart_A node in the future and providing the corresponding
> GPIOs there

Good.  I didn't like the (ab)use of sdio_pwrseq GPIO resets for the
bluetooth either.

> - all the userspace commands will not be necessary once
> drivers/bluetooth/hci_bcm.c is changed to the serio framework and gets
> devicetree support

Cool.  Maybe you can setup a WIP branch based on Rob's work for broader
testing on Amlogic boards until this gets merged?

In the mean time, I've applied patch 2/4 and hopefully the drivers/tty
patch will go through the serial tree.


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