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

From: Robin Murphy
Date: Tue May 14 2019 - 11:19:21 EST

+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
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:


Thank you!

For context, see thread here:

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(-)