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Date:   Tue, 14 May 2019 20:29:31 +0200
From:   Fredrik Noring <noring@nocrew.org>
To:     Robin Murphy <robin.murphy@arm.com>
Cc:     laurentiu.tudor@nxp.com, hch@lst.de, stern@rowland.harvard.edu,
        gregkh@linuxfoundation.org, linux-usb@vger.kernel.org,
        marex@denx.de, JuergenUrban@gmx.de, leoyang.li@nxp.com,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 0/3] prerequisites for device reserved local mem
 rework
Message-ID: <20190514182931.GA2559@sx9>
References: <20190514143807.7745-1-laurentiu.tudor@nxp.com>
 <9d34015d-c219-179b-3141-4b0de3530ac3@arm.com>
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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