> The Raspberry Pi support in edk2-platforms, including ACPI, is a direct > ancestor of the original ms-iot tree (https://github.com/ms-iot/RPi-UEFI, by > way of https://github.com/andreiw/RaspberryPiPkg). > The way the miniUART is described in ACPI came from Microsoft. Microsoft > introduced DBG2/SPCR type 0x10 > (https://docs.microsoft.com/en-us/windows-hardware/drivers/bringup/acpi-debug-port-table) > and the BCM2836 _HID to describe the miniUART, and the contract is that the > base address includes all those crazy registers. > > To the best of my knowledge, today there isn't any other way to correctly > describe the miniUART in a DBG2, SPCR or DSDT. Moreover, because there's code > out there in at least two operating systems coded against these specific > definitions, you don't get to change how a _HID == BCM2836 device or > SPCR/DBG2 type 0x10 is described.
Thanks for your feedback! I only had Linux in mind and didn't think about the other implementations that would break. Thank you for stating the historical reasons why things are set that way, I better understand now and see why this patch wouldn't be such a great idea. > I guess I wasn't clear, I wasn't suggesting we change the existing > mechanism, so yes, I agree we either need another mechanism, or linux is > going to have to deal with it as is. The latter is IMHO the best option > (and as I mentioned I have patches to make it work), but sort of moves > us away from the standard uart/etc mechanisms we want for systemready. > So in that regard its not ideal. I'm very interested to play with your patches if you could send them :) I've been trying to add ACPI support to the miniuart Linux driver, and stumbled across two issues: - the miniuart base address "off by 0x40" in the DSDT (the subject of this thread) - how to properly get the clock rate with ACPI Ideally, the end goal would be to have both the serial console and BT working with the miniuart. Adrien -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#84835): https://edk2.groups.io/g/devel/message/84835 Mute This Topic: https://groups.io/mt/87501357/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
