ср, 21 черв. 2023 р. о 13:32 Andi Shyti <andi.shyti@xxxxxxxxxx> пише: > > Hi, > > On Mon, Jun 19, 2023 at 06:37:32PM +0300, Svyatoslav Ryhel wrote: > > From: Michał Mirosław <mirq-linux@xxxxxxxxxxxx> > > > > Implement driver for hot-plugged I2C busses, where some devices on > > a bus are hot-pluggable and their presence is indicated by GPIO line. > > > > Co-developed-by: Ion Agorria <ion@xxxxxxxxxxx> > > Signed-off-by: Ion Agorria <ion@xxxxxxxxxxx> > > Signed-off-by: Michał Mirosław <mirq-linux@xxxxxxxxxxxx> > > Signed-off-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx> > > --- > > drivers/i2c/Kconfig | 11 ++ > > drivers/i2c/Makefile | 1 + > > drivers/i2c/i2c-hotplug-gpio.c | 266 +++++++++++++++++++++++++++++++++ > > 3 files changed, 278 insertions(+) > > create mode 100644 drivers/i2c/i2c-hotplug-gpio.c > > without going through the code I am missing the big picture here. > > What is this actually doing? Basically it duplicates the parent i2c bus once detection GPIO triggers and probes all hot-pluggable devices which are connected to it. Once GPIO triggers detach signal all hot-pluggable devices are unprobed and bus removed. > Is this a new bus driver support? Most likely not. > Is this a feature to existing drivers? Yes, it is more like i2c mux > Is the GPIO an irq line for signalling hoplugging and can be used by > any driver or just this one? > It can be shared if necessary but usually all hot-pluggable devices are gathered in one container and are plugged simultaneously. > Without further discussing technicalities, can you please explain > better and more in detail what is the scope of this patch, why > there is a need for such a patch, how this new driver/feature > has been implemented and finally how it can be used. This patch is a predecessor of a possible larger patchset which should bring support for a asus-ec, a i2c mfd device programmed by Asus for their Transformers tablet line. This is Michał Mirosław, original author quote about this driver: "The Transformers have a connector that's used for USB, charging or for attaching a keyboard (called a dock; it also has a battery and a touchpad). This connector probably (I don't have the means to verify that) has an I2C bus lines and a "detect" line (pulled low on the dock side) among the pins. I guess there is either no additional chip or a transparent bridge/buffer chip, but nothing that could be controlled by software. For DT this setup could be modelled like an I2C gate or 2-port mux with enable joining two I2C busses (one "closer" to the CPU -- parent)." Similar approach is used in Microsoft Surface RT for attachable Type Cover. > This would help a lot so that I know already beforehand what I am > going to read without figuring it out. > > Thanks, > Andi > > PS Please notice that my set of questions is even longer than > your commit log :)
