From: Stefan Wahren <wahrenst@gmx.net>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
catalin.marinas@arm.com, hch@lst.de, marc.zyngier@arm.com,
robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-mm@kvack.org, linux-riscv@lists.infradead.org
Cc: f.fainelli@gmail.com, robin.murphy@arm.com,
linux-kernel@vger.kernel.org, mbrugger@suse.com,
linux-rpi-kernel@lists.infradead.org, phill@raspberrypi.org,
will@kernel.org, m.szyprowski@samsung.com
Subject: Re: [PATCH v5 0/4] Raspberry Pi 4 DMA addressing support
Date: Mon, 9 Sep 2019 21:33:43 +0200 [thread overview]
Message-ID: <5a8af6e9-6b90-ce26-ebd7-9ee626c9fa0e@gmx.net> (raw)
In-Reply-To: <20190909095807.18709-1-nsaenzjulienne@suse.de>
Hi Nicolas,
Am 09.09.19 um 11:58 schrieb Nicolas Saenz Julienne:
> Hi all,
> this series attempts to address some issues we found while bringing up
> the new Raspberry Pi 4 in arm64 and it's intended to serve as a follow
> up of these discussions:
> v4: https://lkml.org/lkml/2019/9/6/352
> v3: https://lkml.org/lkml/2019/9/2/589
> v2: https://lkml.org/lkml/2019/8/20/767
> v1: https://lkml.org/lkml/2019/7/31/922
> RFC: https://lkml.org/lkml/2019/7/17/476
>
> The new Raspberry Pi 4 has up to 4GB of memory but most peripherals can
> only address the first GB: their DMA address range is
> 0xc0000000-0xfc000000 which is aliased to the first GB of physical
> memory 0x00000000-0x3c000000. Note that only some peripherals have these
> limitations: the PCIe, V3D, GENET, and 40-bit DMA channels have a wider
> view of the address space by virtue of being hooked up trough a second
> interconnect.
>
> Part of this is solved on arm32 by setting up the machine specific
> '.dma_zone_size = SZ_1G', which takes care of reserving the coherent
> memory area at the right spot. That said no buffer bouncing (needed for
> dma streaming) is available at the moment, but that's a story for
> another series.
>
> Unfortunately there is no such thing as 'dma_zone_size' in arm64. Only
> ZONE_DMA32 is created which is interpreted by dma-direct and the arm64
> arch code as if all peripherals where be able to address the first 4GB
> of memory.
>
> In the light of this, the series implements the following changes:
>
> - Create both DMA zones in arm64, ZONE_DMA will contain the first 1G
> area and ZONE_DMA32 the rest of the 32 bit addressable memory. So far
> the RPi4 is the only arm64 device with such DMA addressing limitations
> so this hardcoded solution was deemed preferable.
>
> - Properly set ARCH_ZONE_DMA_BITS.
>
> - Reserve the CMA area in a place suitable for all peripherals.
>
> This series has been tested on multiple devices both by checking the
> zones setup matches the expectations and by double-checking physical
> addresses on pages allocated on the three relevant areas GFP_DMA,
> GFP_DMA32, GFP_KERNEL:
>
> - On an RPi4 with variations on the ram memory size. But also forcing
> the situation where all three memory zones are nonempty by setting a 3G
> ZONE_DMA32 ceiling on a 4G setup. Both with and without NUMA support.
>
i like to test this series on Raspberry Pi 4 and i have some questions
to get arm64 running:
Do you use U-Boot? Which tree?
Are there any config.txt tweaks necessary?
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next prev parent reply other threads:[~2019-09-09 19:34 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-09 9:58 [PATCH v5 0/4] Raspberry Pi 4 DMA addressing support Nicolas Saenz Julienne
2019-09-09 9:58 ` [PATCH v5 1/4] arm64: mm: use arm64_dma_phys_limit instead of calling max_zone_dma_phys() Nicolas Saenz Julienne
2019-09-09 9:58 ` [PATCH v5 2/4] arm64: rename variables used to calculate ZONE_DMA32's size Nicolas Saenz Julienne
2019-09-09 9:58 ` [PATCH v5 3/4] arm64: use both ZONE_DMA and ZONE_DMA32 Nicolas Saenz Julienne
2019-09-11 10:54 ` Nicolas Saenz Julienne
2019-09-11 14:35 ` Catalin Marinas
2019-09-11 15:00 ` Nicolas Saenz Julienne
2019-09-09 9:58 ` [PATCH v5 4/4] mm: refresh ZONE_DMA and ZONE_DMA32 comments in 'enum zone_type' Nicolas Saenz Julienne
2019-09-09 19:33 ` Stefan Wahren [this message]
2019-09-09 19:50 ` [PATCH v5 0/4] Raspberry Pi 4 DMA addressing support Nicolas Saenz Julienne
2019-09-10 9:27 ` Matthias Brugger
2019-09-12 17:18 ` Matthias Brugger
2019-09-12 17:27 ` Florian Fainelli
2019-09-12 19:32 ` Stefan Wahren
2019-09-13 7:15 ` Matthias Brugger
2019-09-13 8:09 ` Matthias Brugger
2019-09-13 8:50 ` Stefan Wahren
2019-09-13 9:25 ` Matthias Brugger
2019-09-13 10:08 ` Stefan Wahren
2019-09-13 10:39 ` Matthias Brugger
2019-09-16 19:19 ` Stefan Wahren
2019-09-17 9:04 ` Matthias Brugger
2019-09-17 18:03 ` Stefan Wahren
2019-09-27 16:44 ` Stefan Wahren
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