On Fri, 2020-12-11 at 08:44 +0100, Greg KH wrote: > On Thu, Dec 10, 2020 at 11:04:11PM -0800, Hemant Kumar wrote: > > This MHI client driver allows userspace clients to transfer > > raw data between MHI device and host using standard file > > operations. > > Driver instantiates UCI device object which is associated to device > > file node. UCI device object instantiates UCI channel object when > > device > > file node is opened. UCI channel object is used to manage MHI > > channels > > by calling MHI core APIs for read and write operations. MHI > > channels > > are started as part of device open(). MHI channels remain in start > > state until last release() is called on UCI device file node. > > Device > > file node is created with format > > > > /dev/<mhi_device_name> > > > > Currently it supports QMI channel. libqmi is userspace MHI client > > which > > communicates to a QMI service using QMI channel. libqmi is a glib- > > based > > library for talking to WWAN modems and devices which speaks QMI > > protocol. > > For more information about libqmi please refer > > https://www.freedesktop.org/wiki/Software/libqmi/ > > This says _what_ this is doing, but not _why_. > > Why do you want to circumvent the normal user/kernel apis for this > type > of device and move the normal network handling logic out to > userspace? > What does that help with? What does the current in-kernel api lack > that > this userspace interface is going to solve, and why can't the in- > kernel > api solve it instead? > > You are pushing a common user/kernel api out of the kernel here, to > become very device-specific, with no apparent justification as to why > this is happening. > > Also, because you are going around the existing network api, I will > need > the networking maintainers to ack this type of patch.
Just to re-iterate: QMI ~= AT commands ~= MBIM (not quite, but same level) We already do QMI-over-USB, or AT-over-CDC-ACM. This is QMI-over-MHI. It's not networking data plane. It's WWAN device configuration. There are no current kernel APIs for this, and I really don't think we want there to be. The API surface is *huge* and we definitely don't want that in-kernel. Dan
