APPLIED/cmt: [PATCH 0/2] [C-D/master][SRU] arm64: snapdragon: Fix bluetooth controller

[Stefan Bader]

On 28.01.19 02:05, Khaled Elmously wrote:
> Applied to cosmic/master-next. But this bug isn't nominated for Cosmic

Nominated and set to committed.

-Stefan
> 
> 
> 
> On 2019-01-22 17:20:28 , Paolo Pisati wrote:
>> Exactly the same patches that landed in B/master, this time for Cosmic and
>> Disco / master - mechanical modification to make the config patches apply,
>> while the SAUCE patch is identical - i already applied cking and smb acks.
>>
>> --
>>
>> 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(+)
>>
>> -- 
>> 2.7.4
>>
>>
>> -- 
>> kernel-team mailing list
>> kernel-team at lists.ubuntu.com
>> https://lists.ubuntu.com/mailman/listinfo/kernel-team
> 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: OpenPGP digital signature
URL: <https://lists.ubuntu.com/archives/kernel-team/attachments/20190128/1f1e9e7e/attachment-0001.sig>