On Mon, Oct 09, 2017 at 10:55:34AM +0200, Sebastian Reichel wrote: > 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. 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. > > 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. In general, yes. Again, the only exception would be hci_bcm to avoid breaking current setups without people noticing. > 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. I'm not saying it's a fix, but it is a sane default. I'm preparing a patch also amending the Kconfig entries, and we can take it from there. Johan -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
