On Wed, Dec 16, 2020 at 10:17:30AM +0100, Loic Poulain wrote: > Hi Folks, > > On Fri, 11 Dec 2020 at 20:45, Hemant Kumar <hemantk@xxxxxxxxxxxxxx> wrote: > > > > This patch series adds support for UCI driver. UCI driver enables userspace > > clients to communicate to external MHI devices like modem. UCI driver probe > > creates standard character device file nodes for userspace clients to > > perform open, read, write, poll and release file operations. These file > > operations call MHI core layer APIs to perform data transfer using MHI bus > > to communicate with MHI device. > > > > This interface allows exposing modem control channel(s) such as QMI, MBIM, > > or AT commands to userspace which can be used to configure the modem using > > tools such as libqmi, ModemManager, minicom (for AT), etc over MHI. This is > > required as there are no kernel APIs to access modem control path for device > > configuration. Data path transporting the network payload (IP), however, is > > routed to the Linux network via the mhi-net driver. Currently driver supports > > QMI channel. libqmi is userspace MHI client which communicates to a QMI > > service using QMI channel. Please refer to > > https://www.freedesktop.org/wiki/Software/libqmi/ for additional information > > on libqmi. > > > > Patch is tested using arm64 and x86 based platform. > > Are there any blockers or unadressed comments remaining on this > series? As far as I understand, the original blocker was the net/WiFi > mention in the commit message, that caused a legitimate concern from > network maintainer. It has been clarified now that this driver is not > for exposing any channel that could be otherwise handled properly by > an existing Linux subsystem/interface. It will be especially used as a > pipe for modem QMI channel (or AT commands) in the same way as the USB > CDC-WDM driver is doing (keeping userspace compatibility). Other MHI > channels, such as network data, QRTR, etc are not exposed and > correctly bound to the corresponding Linux subsystems. > > The correlated worry was that it could be a userspace channel facility > for 'everything qualcomm', but we could say the same for other > existing busses with userspace shunt (/dev/bus/usb, /dev/i2c, > /dev/spidev, PCI UIO, UART...). Moreover, it is mitigated by the fact > that not all MHI channels are exposed by default, but only the allowed > ones (QMI in the initial version). For sure, special care must be > given to any further channel addition. It's the middle of the merge window, we can't do anything with new patches at all until 5.11-rc1 is out, so please be patient. thanks, greg k-h
