Hi Carlo, On Wed, Jan 3, 2018 at 12:06 AM, Carlo Caione <carlo@xxxxxxxxxxxx> wrote: > On Tue, Jan 2, 2018 at 9:46 PM, Martin Blumenstingl > <martin.blumenstingl@xxxxxxxxxxxxxx> wrote: >> Hi Carlo, > > Hi Martin, > >> On Tue, Jan 2, 2018 at 12:31 PM, Carlo Caione <carlo@xxxxxxxxxxxx> wrote: >>> On Tue, Jan 2, 2018 at 11:19 AM, Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote: >>>> Hi Carlo, >>>> >>>>>>> Some Realtek bluetooth devices need a "config" blob. The btrtl driver >>>>>>> currently only allows loading this config blob via the request_firmware >>>>>>> mechanism. >>>>>>> >>>>>>> The UART Bluetooth chips use this config blob to specify the baudrate, >>>>>>> whether flow control is used and some other unknown bits. This means >>>>>>> that the config blob is board-specific - thus loading it via >>>>>>> request_firmware means that the rootfs is tied to a specific board. >>>>>>> >>>>>>> The UART Bluetooth chips are implemented through serdev. This means >>>>>>> there is also a devicetree node which describes the Bluetooth chip. >>>>>>> Thus we can also load the blob from the devicetree node to keep the >>>>>>> filesystem independent of any board configuration data. In the future >>>>>>> this could be extended to support ACPI as well (in case that's needed). >>>>>>> >>>>>>> Parse the devicetree node if it exists and obtain the config blob from >>>>>>> there. Otherwise fall back to using the "old" request_firmware >>>>>>> mechanism. >>>>>> >>>>>> where are these config blobs coming from? I think we also need to give people a helping hand on how to add them to DT. I still wonder if the only pieces we are using are the UART config, then maybe skipping the config blob and allowing for clear named values in DT might be better. >>>>> >>>>> What about x86 platforms where we do not have DT (I didn't check but I >>>>> don't think that the UART config in that case is shipped in the ACPI >>>>> tables)? >>>> >>>> if we have this hardware in x86 systems, then I would really like to see ACPI table dumps. Some pieces might need hardcoding based on ACPI ID. >>> >>> Yes, we have, especially on cherry-trail SoCs. In [0] the DSDT of a >>> cherry-trail laptop shipping the rtl8723bs (device OBDA8723). >>> >>> [0] https://gist.github.com/carlocaione/82bff95ababb67dd33f52a86e94ce3ff >> so this shows that the UART settings (initial baudrate, HW flow >> control, etc.) are part of the DSDT >> however, the actual config blob is not >> >> the description of this patch explains: "Parse the devicetree node ... >> [or] ... fall back to using the "old" request_firmware mechanism." >> do you have any other solution in mind? > > As Marcel suggested we can assume that the information in the DSDT is > correct so that we can get rid of the config blob also for x86 > platforms (assuming that the only useful information in the config > blobs is the UART configuration). in my tests I tried to send only the firmware without the config to my RTL8723BS. unfortunately the last firmware chunk (sent to the controller) times out in that case (even if I set a proper baudrate before or if I specify no baudrate at all and keep the serdev at 115200) have you tested this (= uploading the firmware without the config blob) on your x86 board before? so far the following solutions for the config blob were discussed: 1) put the config blob in userspace (/lib/firmware/...) -> not good because it makes the rootfs board-specific 2) auto-generate the config blob -> didn't work for me, last firmware chunk times out (just as if I had no config at all) 3) putting the config blob in DT -> possible but not very nice to read I had another idea: what if we mix solution 1) and 2)? the idea: load the config blob from userspace (/lib/firmware/...) and update it's settings with the values we got from devicetree-properties / DSDT I have not tested this yet, but I just want to hear everyone's (at least Marcel, Rob and Carlo) opinion on that (this would also allow us to fully auto-generate the config blob in the future once we figure out how to do that) > Adding the ACPI support on top of your patches is (hopefully) trivial, > just follow what was done for hci_bcm.c, basically adding a new _HID > and reading the configuration for GPIOs and UART, all the rest should > be transparent for serdev. thanks for the reference to hci_bcm.c - I will have a look at this for the next version one question: "_HID" would be OBDA8723 in our case? > I'll test your patches on the hardware I have. great, thank you! Regards Martin -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
