On Mon, 20 Nov 2017 12:57:56 +0200 Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > +Jarkko > > On Sun, Nov 19, 2017 at 04:35:51PM +0000, Jonathan Cameron wrote: > > On Thu, 2 Nov 2017 16:04:07 +0100 > > Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote: > > > > > On Thu, Nov 02, 2017 at 02:35:50PM +0000, Jonathan Cameron wrote: > > > > On Fri, 27 Oct 2017 18:27:02 +0200 > > > > Marc CAPDEVILLE <m.capdeville@xxxxxxxxxx> wrote: > > > > > > > > > On asus T100, Capella cm3218 chip is implemented as ambiant light > > > > > sensor. This chip expose an smbus ARA protocol device on standard > > > > > address 0x0c. The chip is not functional before all alerts are > > > > > acknowledged. > > > > > On asus T100, this device is enumerated on ACPI bus and the > > > > > description give tow I2C connection. The first is the connection to > > > > > the ARA device and the second gives the real address of the device. > > > > > > > > > > So, on device probe,If the i2c address is the ARA address and the > > > > > device is enumerated via acpi, we lookup for the real address in > > > > > the ACPI resource list and change it in the client structure. > > > > > if an interrupt resource is given, and only for cm3218 chip, > > > > > we declare an smbus_alert device. > > > > > > > > > > Signed-off-by: Marc CAPDEVILLE <m.capdeville@xxxxxxxxxx> > > > > > > > > Wolfram - this needs input from you on how to neatly handle > > > > an ACPI registered ARA. > > > > > > ACPI is really not my field. Try asking the I2C ACPI maintainers or > > > Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> who did work on SMBus > > > interrupts recently. > > > > > Hi Mika, Benjamin, > > > > So we've lost most of the context in this thread, but the basic question > > is how to handle smbus ARA support with ACPI. > > > > https://patchwork.kernel.org/patch/10030309/ > > > > Has the proposal made in this driver which is really not terribly nice > > (as it registers the ARA device by messing with the address and registering > > a second device). > > > > As I understood it the ARA device registration should be handled by the > > i2c master, but there are very few examples. > > > > Phil pointed out that equivalent OF support recently got taken from him.. > > https://www.spinics.net/lists/devicetree/msg191947.html > > https://www.spinics.net/lists/linux-i2c/msg31173.html > > > > Any thoughts on the right way to do this? > > There does not seem to be any way in ACPI to tell which "connection" is > used to describe ARA so that part currently is something each driver > needs to handle as they know the device the best. I don't think we have > any means to handle it in generic way in I2C core except to provide some > helpers that work on top of i2c_setup_smbus_alert() but understand ACPI > resources. Say provide function like this: > > int acpi_i2c_setup_smbus_alert(struct i2c_adapter *adapter, int index); > > Which then extracts automatically I2cSerialBus connection from "index" > and calls i2c_setup_smbus_alert() accordingly. > > In the long run we could introduce _DSD property that can be used to > name the connection in the same way DT does; > > Name (_CRS, ResourceTemplate () { > I2cSerialBus () { ... } // ARA > I2cSerialBus () { ... } // normal device address > }) > > Name (_DSD, Package () { > ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"), > Package () { > Package () {"smbus_alert", 0} // Where 0 means the first I2cSerialBus > ... > } > }) > > But it does not help the existing systems. I'm curious - how would we go about promoting this piece of common sense? Jonathan > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
