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Message-ID: <21a7276e98ae245404d82537ac1ee597a92f9150.camel@suse.de>
Subject: Re: [PATCH] dma-pool: use single atomic pool for both DMA zones
From:   Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To:     Jeremy Linton <jeremy.linton@arm.com>,
        Christoph Hellwig <hch@lst.de>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Robin Murphy <robin.murphy@arm.com>,
        David Rientjes <rientjes@google.com>
Cc:     linux-rpi-kernel@lists.infradead.org,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Date:   Wed, 08 Jul 2020 12:35:34 +0200
In-Reply-To: <e6504dc5-4169-edf9-d08e-17a378a1ef7a@arm.com>
References: <20200707122804.21262-1-nsaenzjulienne@suse.de>
         <e6504dc5-4169-edf9-d08e-17a378a1ef7a@arm.com>
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Hi Jim,

On Tue, 2020-07-07 at 17:08 -0500, Jeremy Linton wrote:
> Hi,
>=20
> I spun this up on my 8G model using the PFTF firmware from:
>=20
> https://github.com/pftf/RPi4/releases
>=20
> Which allows me to switch between ACPI/DT on the machine. In DT mode it=
=20
> works fine now,=20

Nice, would that count as a Tested-by from you?

> but with ACPI I continue to have failures unless I=20
> disable CMA via cma=3D0 on the kernel command line.=20

Yes, I see why, in atomic_pool_expand() memory is allocated from CMA withou=
t
checking its correctness. That calls for a separate fix. I'll try to think =
of
something.

> It think that is because
>=20
> using DT:
>=20
> [    0.000000] Reserved memory: created CMA memory pool at
> 0x0000000037400000, size 64 MiB
>=20
>=20
> using ACPI:
> [    0.000000] cma: Reserved 64 MiB at 0x00000000f8000000
>=20
> Which is AFAIK because the default arm64 CMA allocation is just below=20
> the arm64_dma32_phys_limit.

As I'm sure you know, we fix the CMA address trough DT, isn't that possible
trough ACPI?

Regards,
Nicolas


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