Re: [RESEND PATCH v18 0/3] userspace MHI client interface driver

Manivannan Sadhasivam
2021-02-03T04:16:20Z

Hi Jakub,

On 3 February 2021 9:40:08 AM IST, Jakub Kicinski <kuba@kernel.org> wrote:
>On Tue, 2 Feb 2021 09:52:08 +0530 Manivannan Sadhasivam wrote:
>> > > I don't see the connection here, sorry.
>> >
>> > For instance USB_NET_CDC_MBIM driver creates the /dev/cdc-wdmX
>chardev node for
>> > configuring the modems which supports MBIM protocol over USB. Like
>that, this
>> > driver creates /dev/mhiX_MBIM chardev node for configuring the
>modem over MHI
>> > bus instead of USB. The question arised why we are creating a
>chardev node for
>> > each supported configuration (channels in the case of MHI) and why
>can't we use
>> > the existing /dev/cdc-wdmZ interfaces? The anwser is there is no
>standard
>> > subsystem for WWAN and all the drivers represent a chardev which
>gets used by
>> > the userspace tools such a Network manager for establishing
>connection.
>> >
>> > And /dev/cdc-wdmX is restricted to the USB CDC devices.
>> >
>> > Hope this clarifies!
>>
>> Jakub, Dave, Adding you both to get your reviews on this series. I've
>> provided an explanation above and in the previous iteration [1].
>
>Let's be clear what the review would be for. Yet another QMI chardev
>or the "UCI" direct generic user space to firmware pipe?

The current patchset only supports QMI channel so I'd request you to review the chardev node created for it. The QMI chardev node created will be unique for the MHI bus and the number of nodes depends on the MHI controllers in the system (typically 1 but not limited).

Thanks,
Mani

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