On Tue, 1 Dec 2020 12:40:50 -0700 Jeffrey Hugo wrote: > On 12/1/2020 12:29 PM, Jakub Kicinski wrote: > > On Fri, 27 Nov 2020 19:26:02 -0800 Hemant Kumar wrote: > >> This patch series adds support for UCI driver. UCI driver enables userspace > >> clients to communicate to external MHI devices like modem and WLAN. 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. Patch is tested using arm64 based platform. > > > > Wait, I thought this was for modems. > > > > Why do WLAN devices need to communicate with user space? > > > > Why does it matter what type of device it is? Are modems somehow unique > in that they are the only type of device that userspace is allowed to > interact with? Yes modems are traditionally highly weird and require some serial device dance I don't even know about. We have proper interfaces in Linux for configuring WiFi which work across vendors. Having char device access to WiFi would be a step back. > However, I'll bite. Once such usecase would be QMI. QMI is a generic > messaging protocol, and is not strictly limited to the unique operations > of a modem. > > Another usecase would be Sahara - a custom file transfer protocol used > for uploading firmware images, and downloading crashdumps. Thanks, I was asking for use cases, not which proprietary vendor protocol you can implement over it. None of the use cases you mention here should require a direct FW - user space backdoor for WLAN. > Off the top of my head, this driver is useful for modems, wlan, and AI > accelerators. And other Qualcomm products are available as well :/ Kernel is supposed to create abstract interfaces for user space to utilize. I will never understand why kernel is expected to be in business of shipping this sort of vendor backdoors :/
