[PATCH 0/2] [B/master][SRU] arm64: snapdragon: Fix bluetooth controller in Dragonboard410c

[Paolo Pisati]

Uhm, good point, i didn't check there (since Ubuntu Core is using
Bionic kernel), but i'll do.

On Mon, Jan 21, 2019 at 3:32 PM Stefan Bader <stefan.bader at canonical.com> wrote:
>
> On 16.01.19 16:55, Paolo Pisati wrote:
> > BugLink: https://bugs.launchpad.net/bugs/1810797
> >
> > Impact:
> >
> > Upon boot, no hci device is available to userspace, thus bluetooth
> > communication is not possible.
> >
> > Defect analysis:
> >
> > The root of the problem lies in these two patches:
> >
> > $ git log --online drivers/bluetooth/btqcomsmd.c
> >
> > ...
> > 766154b Bluetooth: btqcomsmd: retrieve BD address from DT property
> > 6e51811 Bluetooth: btqcomsmd: Add support for BD address setup
> > ...
> >
> > Qualcomm engineer found that btqcomsmd had no BD address burned in (nor
> > via ROM, neither internally) and it was always coming up with the same
> > address, probably derived from manufacturer ID and / or chip ID.
> >
> > To fix this, they pushed the burden of generating a unique per-board BD
> > address to the Qualcomm bootloader and make it pass down via DTB to the
> > live kernel - and if no address was present in the DTB, the hci was left
> > unconfigured.
> >
> > Fix:
> >
> > So *technically* speaking, the kernel is correct in this case, it's our
> > dragonboard image (e.g. Ubuntu Core) that doesn't extract the generated
> > BD address from the Qualcomm bootloader and pass it down to the kernel.
> >
> > On the other hand, having Bluetooth working out of the box (even with a
> > dummy address), is a nice feature to have, so i slightly modified
> > Qualcomm's code introduced in the two above patches, and made the lack
> > of BD address in DTB non fatal:
> >
> > if BD_is_present_in_DTB()
> >     read_BD_and_apply_setup()
> > else
> >     let_hci_core_generate_BD()
> > end if
> >
> > And surrounded the modification in #ifdef...#endif brackets to keep it
> > local.
> >
> > How to test:
> >
> > By default, on a patched kernel, the hci device will have a default
> > address:
> >
> > ubuntu at dragon410c:~$ hcitool dev
> > Devices:
> >         hci0 00:00:00:00:5A:AD
> >
> > the address " 00:00:00:00:5A:AD" might vary, but will be consistent
> > after every reboot.
> >
> > The other option is to specify a custom BD address, e.g. using uboot to
> > manipulate the dtb - we assume the dtb was loaded in memory at
> > ${fdt_addr}:
> >
> > dragonboard410c => fdt addr ${fdt_addr}
> >
> > dragonboard410c => fdt print /soc/wcnss/smd-edge/wcnss/bt/
> > bt {
> >         compatible = "qcom,wcnss-bt";
> > };
> >
> > dragonboard410c => fdt resize
> >
> > dragonboard410c => fdt set /soc/wcnss/smd-edge/wcnss/bt/
> > local-bd-address [ 55 44 33 22 11 00 ]
> >
> > dragonboard410c => fdt print /soc/wcnss/smd-edge/wcnss/bt/
> > bt {
> >         local-bd-address = [55 44 33 22 11 00];
> >         compatible = "qcom,wcnss-bt";
> > };
> >
> > then proceed with the rest of the boot process and check hci:
> >
> > $ hcitool dev
> > Devices:
> >         hci0 00:11:22:33:44:55
> >
> > In both cases, blueooth work afterward, and can be used to communicate
> > with other devices:
> >
> > ubuntu at dragon410c:~$ hcitool scan
> > Scanning ...
> >         C0:BD:54:12:4E:D1 My dummy device
> >
> > Regression potential:
> >
> > None, the fix is surronded with #ifdef...#endif thus it doesn't exist
> > outside of it.
> >
> > Paolo Pisati (2):
> >   UBUNTU: SAUCE: btqcomsmd: introduce BT_QCOMSMD_HACK
> >   UBUNTU: [Config] arm64: snapdragon: BT_QCOMSMD_HACK=y
> >
> >  debian.master/config/amd64/config.common.amd64       | 1 +
> >  debian.master/config/arm64/config.flavour.generic    | 1 +
> >  debian.master/config/arm64/config.flavour.snapdragon | 1 +
> >  debian.master/config/armhf/config.common.armhf       | 1 +
> >  debian.master/config/i386/config.common.i386         | 1 +
> >  debian.master/config/ppc64el/config.common.ppc64el   | 1 +
> >  drivers/bluetooth/Kconfig                            | 7 +++++++
> >  drivers/bluetooth/btqcomsmd.c                        | 5 +++++
> >  8 files changed, 18 insertions(+)
> >
>
> Oh ... what about Cosmic/Disco/Unstable?
>


-- 
bye,
p.