Re: [RFC PATCH v2 0/3] prerequisites for device reserved local mem rework

Fredrik Noring
2019-05-14T18:39:18Z

Thanks Robin!

> > For HCs that have local memory, replace the current DMA API usage
> > with a genalloc generic allocator to manage the mappings for these
> > devices.
> > This is in preparation for dropping the existing "coherent" dma
> > mem declaration APIs. Current implementation was relying on a short
> > circuit in the DMA API that in the end, was acting as an allocator
> > for these type of devices.
> >
> > Only compiled tested, so any volunteers willing to test are most welcome.
>
> I recall an out-of-tree PlayStation 2 OHCI driver being another
> HCD_LOCAL_MEM user - if Fredrik and Juergen are still active on that,
> hopefully they might be able to comment on whether this approach can
> work for them too. Patchwork link just in case:
> https://patchwork.kernel.org/project/linux-usb/list/?series=117433

True. In fact I'm preparing a patch submission for this PS2 OHCI driver,
along with about a hundred other patches (unrelated to the USB subsystem).
Hopefully in a few weeks. My patches are currently on top of v5.0. What
branch/version is recommended to try this DMA update?

Here is the v5.0.11 PS2 OHCI driver, for reference:

https://github.com/frno7/linux/blob/ps2-v5.0.11/drivers/usb/host/ohci-ps2.c

Fredrik