Re: [PATCH v3 01/28] xhci: Add support to allocate several interrupters

[Wesley Cheng]

Hi Mathias,

On 3/10/2023 7:07 AM, Mathias Nyman wrote:
> On 9.3.2023 1.57, Wesley Cheng wrote:
> > From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
> >
> > Introduce xHCI APIs to allow for clients to allocate and free
> > interrupters.  This allocates an array of interrupters, which is based on
> > the max_interrupters parameter.  The primary interrupter is set as the
> > first entry in the array, and secondary interrupters following after.
>
> I'm thinking about changing this offloading xHCI API
> xhci should be aware and keep track of which devices and endpoints that
> are offloaded to avoid device getting offloaded twice, avoid xhci driver
> from queuing anything itself for these, and act properly if the offloaded
> device or entire host is removed.
>
> So first thing audio side would need to do do is register/create an
> offload entry for the device using the API:
>
> struct xhci_sideband *xhci_sideband_register(struct usb_device *udev)
>
> (xHCI specs calls offload sideband)
> Then endpoints and interrupters can be added and removed from this
> offload entry
>
> I have some early thoughts written as non-compiling code in:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git 
> feature_interrupters
> https://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git/log/?h=feature_interrupters 
>
>
> Let me know what you think about this.

The concept/framework you built looks good to me.  Makes sense to have 
XHCI better maintain the offloading users.  One thing I would request is 
to move xhci-sideband.h to the include directory since the class driver 
levels would need to be able to reference the structure and APIs you've 
exposed.

I have yet to try it with our implementation, but I'll work on plugging 
it in and fix any issues I see along the way.

Thanks
Wesley Cheng