On Wednesday 28 February 2024 13:50:27 Hans de Goede wrote: > Hi, > > On 2/27/24 23:37, Andy Shevchenko wrote: > > On Tue, Feb 27, 2024 at 11:50 PM Pali Rohár <pali@xxxxxxxxxx> wrote: > >> On Tuesday 27 February 2024 23:19:19 Andy Shevchenko wrote: > >>> On Tue, Feb 27, 2024 at 11:04 PM Pali Rohár <pali@xxxxxxxxxx> wrote: > > > > ... > > > >>> I'm wondering why we need all this. We have notifiers when a device is > >>> added / removed. We can provide a board_info for the device and attach > >>> it to the proper adapter, no? > >> > >> I do not know how flexible are notifiers. Can notifier call our callback > >> when new "struct i2c_adapter *adapter" was instanced? > > > > You can follow notifications of *an* I2C adapter being added / > > removed. With that, you can filter which one is that. Based on that > > you may attach a saved (at __init as you talked about in the reply to > > Hans) board_info with all necessary information. > > > > Something like this (combined) > > https://elixir.bootlin.com/linux/latest/source/drivers/ptp/ptp_ocp.c#L4515 > > https://elixir.bootlin.com/linux/latest/source/drivers/input/mouse/psmouse-smbus.c#L194 > > drivers/platform/x86/touchscreen_dmi.c actually already does something > like this for i2c-clients. The problem is that this brings probe-ordering > problems with it. If the i801 driver is loaded before the dell-smo8800 > driver then the notifiers will not trigger since the i2c-adapter has > already been created (1). > > So we would still need a "cold-plug" manual scan in smo8800_probe() > anyways at which point we might as well just return -EPROBE_DEFER > when the adapter is not there. And that it example why the current existing solution is better, it does not have such problems like the proposed. > As for Pali's suggestion of having the i2c-i801 code call a symbol > exported by dell-smo8800 I did not suggest that! Please do not make false statements about me. > that will cause the dell-smo8800 driver > to load on all x86 devices with an i2c-i801 controller (pretty > much all of them). Slowing the boot and eating memory.
