Hi Luiz, Thanks for looking at this. I did see the main.conf file, and the documentation is fairly clear, but I think there is still a bug here. Mainly: if one enables the experiment via main.conf, but the driver for the kernel has not set the relevant quirk indicating that the device supports the functionality, we are still seeing "central-peripheral" listed as supported. Ultimately this leads to test failures for us as, believing that the functionality is supported, we execute tests that then fail (this is reproducible if you modify a test device's driver to not support this feature (for btusb I removed BTUSB_VALID_LE_STATES as an attribute) and enable the feature via main.conf). In code, I think the culprit is seen in this function in that the value of "action" is set exclusively by the main.conf file, and is then passed into "feat->func" which adds it to "adapter->exps" (at least for this feature). Given what you've said here, I believe the right solution would be to require that both the feature be supported (as derived from the driver) and enabled (as derived from main.conf) in order to consider the feature enabled (as reported to peers/via query). On Tue, Dec 21, 2021 at 2:57 PM Luiz Augusto von Dentz <luiz.dentz@xxxxxxxxx> wrote: > > Hi Jesse, > > On Mon, Dec 20, 2021 at 5:59 PM Jesse Melhuish <melhuishj@xxxxxxxxxxxx> wrote: > > > > --- > > The observed behavior without any change is that support for the > > central-peripheral role can be enabled through an experiment flag in > > BlueZ regardless of whether the controller can actually support it. > > Additionally, if the controller has enabled this feature but the > > experiment flag has not been set the central-peripheral role is not > > listed as supported. I'm not certain what the expected behavior should > > be, but enabling if either source says to enable (this patch) or only > > when both enable the feature both seem like reasonable options to start > > with. > > > > src/adapter.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/src/adapter.c b/src/adapter.c > > index 9fc6853c9..60325015b 100644 > > --- a/src/adapter.c > > +++ b/src/adapter.c > > @@ -10434,7 +10434,8 @@ static void read_exp_features_complete(uint8_t status, uint16_t length, > > } > > > > if (feat->func) > > - feat->func(adapter, action); > > + feat->func(adapter, action || > > + (rp->features[i].flags & BIT(0))); > > Feature being supported doesn't mean the system wants it to be enabled > since this is experimental after all there could be side effects, the > proper way to enable it is via main.conf: > > https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/src/main.conf#n115 > > > } > > } > > } > > -- > > 2.31.0 > > -- > Luiz Augusto von Dentz
