Hi, On Mon, Oct 09, 2017 at 09:35:26AM +0200, Johan Hovold wrote: > On Sun, Oct 08, 2017 at 12:53:11AM +0200, Sebastian Reichel wrote: > > On Sat, Oct 07, 2017 at 05:19:34PM +0200, Johan Hovold wrote: > > > On Wed, Oct 04, 2017 at 10:51:30AM +0200, Frédéric Danis wrote: > > > > 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. 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. > And the bluetooth uart drivers already depend on SERIAL_DEV_BUS. Yes and that's the correct dependency. They only need the serdev core and controller. The only reason they do not work without SERIAL_DEV_CTRL_TTYPORT is, that there won't be any serdev controller. Note, that the default "y" if SERIAL_DEV_BUS in SERIAL_DEV_CTRL_TTYPORT's config entry is only a partial fix. There is still the problem, that SERIAL_DEV_CTRL_TTYPORT can only be enabled if SERIAL_DEV_BUS is configured builtin. This is a limitation of the ttyport implementation, that hooks into builtin TTY core code. -- Sebastian
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