Hi Dragan, On Wed, Nov 13, 2024 at 11:38 AM Dragan Simic <dsimic@xxxxxxxxxxx> wrote: > > Hello Tamas, > > On 2024-11-13 11:24, Tamás Szűcs wrote: > > On Wed, Nov 13, 2024 at 12:25 AM Dragan Simic <dsimic@xxxxxxxxxxx> > > wrote: > >> On 2024-11-12 22:04, Tamás Szűcs wrote: > >> > On Tue, Nov 12, 2024 at 4:07 PM Dragan Simic <dsimic@xxxxxxxxxxx> > >> > wrote: > >> >> Please correct me if I'm wrong, but isn't this UART supposed to be > >> >> used for the Bluetooth part of an SDIO WiFi + Bluetooth module, in > >> >> form of a non-standard M.2 module that Radxa sells? > >> > > >> > UART8 is supposed to be used for any radio module connected to the M2E > >> > connector. > >> > It will typically be responsible for Bluetooth or BLE but it could be > >> > 802.15.4 or whatever. In any case, all wanting to use it will need the > >> > uart8 node enabled. > >> > >> I see, but I'm still guessing what's the actual use of enabling the > >> UART8 when it will remain pretty much useless without the additional > >> DT configuration, such as in the WiFi+Bluetooth DT overlay that Jonas > >> sent a bit earlier? > > > > The actual use is device enablement. > > Hmm, I'll need to think more about how it fits together. > > >> I think that the UART8 should be enabled together with something that > >> actually makes use of it, which in this case unfortunately cannot be > >> automatically detected and configured, so it belongs to a DT overlay. > >> I'll get back to this in my next response. > > > > I agree, bluetooth blocks dedicated to specific modules should belong > > to DT overlays. > > > >> >> With that in mind, I see very little sense in just enabling the UART, > >> >> without defining the entire Bluetooth interface, which AFAIK produces > >> > > >> > Defining a bluetooth node would hardwire idiosyncrasies of a given > >> > radio module's Bluetooth core. Sure you could add a sleep clock, all > >> > kind of sideband signals for wakeups, reset, power down, etc. But hey, > >> > some will use them, some won't. I think it's undesirable and > >> > unnecessary. You can hciattach from here and most will work just like > >> > that. Tighter integration or anything special, module specific on top > >> > should be handled individially, on a case-by-case basis. This is a dev > >> > board after all. I say trick of all trades. > >> > > >> >> nasty looking error messages in the kernel log when there's actually > >> >> nothing connected to the UART. > >> > > >> > My dmesg is clean as a whistle > >> > root@rock-3b:~# dmesg | grep -E 'fe6c0000|ttyS0' > >> > [ 0.344818] fe6c0000.serial: ttyS0 at MMIO 0xfe6c0000 (irq = 26, > >> > base_baud = 1500000) is a 16550A > >> > What kind of nasty errors do you recall? > >> > >> Those would be the kernel error messages produced with the Bluetooth > >> DT configuration in place, but with no SDIO module installed. > > > > These are the kernel messages related to UART8 with the uart8 DT node > > enabled and an SDIO module installed. > > Out of curiosity, what M.2 module are you testing it with? https://www.u-blox.com/en/short-range-radio-modules#Host-based and some more you don't see here. Kind regards, Tamas
