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

[Robin Murphy]

+Fredrik, Juergen

On 14/05/2019 15:38, laurentiu.tudor@xxxxxxx wrote:
> From: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>
>
> 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

Robin.

> Thank you!
>
> For context, see thread here: https://lkml.org/lkml/2019/4/22/357
>
> Changes in v2:
>   - use genalloc also in core usb (based on comment from Robin)
>   - moved genpool decl to usb_hcd to be accesible from core usb
>
> Laurentiu Tudor (3):
>    USB: use genalloc for USB HCs with local memory
>    usb: host: ohci-sm501: init genalloc for local memory
>    usb: host: ohci-tmio: init genalloc for local memory
>
>   drivers/usb/core/buffer.c     | 12 ++++++-
>   drivers/usb/host/ohci-hcd.c   | 23 +++++++++++---
>   drivers/usb/host/ohci-sm501.c | 60 +++++++++++++++++++----------------
>   drivers/usb/host/ohci-tmio.c  | 23 +++++++++-----
>   include/linux/usb/hcd.h       |  3 ++
>   5 files changed, 80 insertions(+), 41 deletions(-)