Hi Johan, >>>>>> UART devices is expected to be enumerated by SerDev subsystem. >>>>>> >>>>>> During ACPI scan, serial devices behind SPI, I2C or UART buses are not >>>>>> enumerated, allowing them to be enumerated by their respective parents. >>>>>> >>>>>> Rename *spi_i2c_slave* to *serial_bus_slave* as this will be used for serial >>>>>> devices on serial buses (SPI, I2C or UART). >>>>>> >>>>>> On Macs an empty ResourceTemplate is returned for uart slaves. >>>>>> Instead the device properties "baud", "parity", "dataBits", "stopBits" are >>>>>> provided. Add a check for "baud" in acpi_is_serial_bus_slave(). >>>>>> >>>>>> Signed-off-by: Frédéric Danis <frederic.danis.oss@xxxxxxxxx> >>>>> >>>>> So just to reiterate what I just mentioned in a comment to one of Hans's >>>>> hci_bcm patches: >>>>> >>>>> This one would silently break PM for such devices on any system which >>>>> does not have serdev enabled (as the corresponding platform devices >>>>> would no longer be registered). And with serdev enabled, hciattach >>>>> (btattach) would start failing as the tty device would no longer be >>>>> registered (but I assume everyone is aware of that, and fine with it, by >>>>> now). >>>>> >>>>> Perhaps the hci_bcm driver should start depending on >>>>> SERIAL_DEV_CTRL_TTYPORT when ACPI is enabled? >>>> >>>> ACPI and DT both need SERIAL_DEV_CTRL_TTYPORT to work properly, >>>> since SERIAL_DEV_CTRL_TTYPORT is the only controller implemented >>>> for serdev. If any other controller is implemented that one could >>>> also be used. >>> >>> Not for hci_bcm, right? This particular driver specifically depends on >>> SERIAL_DEV_CTRL_TTYPORT for the ACPI devices and not just any (future) >>> serdev controller (or currently working systems soon breaks silently). >>> >>> I don't think the same is true for the DT case where we do not already >>> have child nodes defined in firmware (and in fact, this driver did not >>> really support DT before serdev). >> >> The serdev ACPI support has been added to the core and not to >> the ttyport and the hci_bcm driver only uses functions from the >> core. As far as I can see the ACPI part would also work fine with >> a different serdev controller. > > Indeed, but you need SERIAL_DEV_CTRL_TTYPORT to avoid silently breaking > current ACPI setups which breaks when this patch is applied (as these > devices all hang off of common serial ports managed by serial core). > >> Of course DT and ACPI currently require SERIAL_DEV_CTRL_TTYPORT, >> since it's the only serdev controller implementation. Also it >> covers most use cases. When SERIAL_DEV_BUS is selected it's >> very likely, that you also want SERIAL_DEV_CTRL_TTYPORT. > >>>> I wonder if we should just hide SERIAL_DEV_CTRL_TTYPORT and enable >>>> it together with SERDEV. I suspect that we won't see any other >>>> controller (it would be a UART device, that is not registered as >>>> tty device) in the next few years and the extra option seems to >>>> confuse people. >>> >>> I agree that it is somewhat confusing. But now that we have both, >>> perhaps simply having SERIAL_DEV_CTRL_TTYPORT default to "y" when >>> SERIAL_DEV_BUS is selected could be a compromise. The Kconfig entry >>> might need to be amended as well (e.g. if only to mention that you >>> need to select a controller as well). >> >> I think we should at least add a default "y" if SERIAL_DEV_BUS. > > I'm preparing a patch. yes, please prepare a patch since the discussion spans multiple email threads now. Lets get this back on track and find a patch that we are all happy with. Regards Marcel -- 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
