From: Robin Murphy <robin.murphy@arm.com>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org, Frank Rowand <frowand.list@gmail.com>,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>,
linux-wireless <linux-wireless@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
"open list:DMA GENERIC OFFLOAD ENGINE SUBSYSTEM"
<dmaengine@vger.kernel.org>,
etnaviv@lists.freedesktop.org,
dri-devel <dri-devel@lists.freedesktop.org>,
xen-devel@lists.xenproject.org, linux-tegra@vger.kernel.org,
Linux Media Mailing List <linux-media@vger.kernel.org>,
linux-pci@vger.kernel.org, Matthias Brugger <mbrugger@suse.com>,
Florian Fainelli <f.fainelli@gmail.com>,
james.quinlan@broadcom.com, Stefan Wahren <wahrenst@gmx.net>,
Dan Williams <dan.j.williams@intel.com>,
freedreno <freedreno@lists.freedesktop.org>
Subject: Re: [PATCH 00/11] of: Fix DMA configuration for non-DT masters
Date: Wed, 25 Sep 2019 16:09:12 +0100 [thread overview]
Message-ID: <e404c65b-5a66-6f91-5b38-8bf89a7697b2@arm.com> (raw)
In-Reply-To: <d1a31a2ec8eb2f226b1fb41f6c24ffb47c3bf7c7.camel@suse.de>
On 25/09/2019 15:52, Nicolas Saenz Julienne wrote:
> On Tue, 2019-09-24 at 16:59 -0500, Rob Herring wrote:
>> On Tue, Sep 24, 2019 at 1:12 PM Nicolas Saenz Julienne
>> <nsaenzjulienne@suse.de> wrote:
>>> Hi All,
>>> this series tries to address one of the issues blocking us from
>>> upstreaming Broadcom's STB PCIe controller[1]. Namely, the fact that
>>> devices not represented in DT which sit behind a PCI bus fail to get the
>>> bus' DMA addressing constraints.
>>>
>>> This is due to the fact that of_dma_configure() assumes it's receiving a
>>> DT node representing the device being configured, as opposed to the PCIe
>>> bridge node we currently pass. This causes the code to directly jump
>>> into PCI's parent node when checking for 'dma-ranges' and misses
>>> whatever was set there.
>>>
>>> To address this I create a new API in OF - inspired from Robin Murphys
>>> original proposal[2] - which accepts a bus DT node as it's input in
>>> order to configure a device's DMA constraints. The changes go deep into
>>> of/address.c's implementation, as a device being having a DT node
>>> assumption was pretty strong.
>>>
>>> On top of this work, I also cleaned up of_dma_configure() removing its
>>> redundant arguments and creating an alternative function for the special
>>> cases
>>> not applicable to either the above case or the default usage.
>>>
>>> IMO the resulting functions are more explicit. They will probably
>>> surface some hacky usages that can be properly fixed as I show with the
>>> DT fixes on the Layerscape platform.
>>>
>>> This was also tested on a Raspberry Pi 4 with a custom PCIe driver and
>>> on a Seattle AMD board.
>>
>> Humm, I've been working on this issue too. Looks similar though yours
>> has a lot more churn and there's some other bugs I've found.
>
> That's good news, and yes now that I see it, some stuff on my series is overly
> complicated. Specially around of_translate_*().
>
> On top of that, you removed in of_dma_get_range():
>
> - /*
> - * At least empty ranges has to be defined for parent node if
> - * DMA is supported
> - */
> - if (!ranges)
> - break;
>
> Which I assumed was bound to the standard and makes things easier.
>
>> Can you test out this branch[1]. I don't have any h/w needing this,
>> but wrote a unittest and tested with modified QEMU.
>
> I reviewed everything, I did find a minor issue, see the patch attached.
WRT that patch, the original intent of "force_dma" was purely to
consider a device DMA-capable regardless of the presence of
"dma-ranges". Expecting of_dma_configure() to do anything for a non-OF
device has always been bogus - magic paravirt devices which appear out
of nowhere and expect to be treated as genuine DMA masters are a
separate problem that we haven't really approached yet.
Robin.
next prev parent reply other threads:[~2019-09-25 15:09 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-24 18:12 [PATCH 00/11] of: Fix DMA configuration for non-DT masters Nicolas Saenz Julienne
2019-09-24 18:12 ` [PATCH 01/11] of: address: clean-up unused variable in of_dma_get_range() Nicolas Saenz Julienne
2019-09-24 18:12 ` [PATCH 02/11] of: base: introduce __of_n_*_cells_parent() Nicolas Saenz Julienne
2019-09-24 18:12 ` [PATCH 03/11] of: address: use parent DT node in bus->count_cells() Nicolas Saenz Julienne
2019-09-24 18:12 ` [PATCH 04/11] of: address: introduce of_translate_dma_address_parent() Nicolas Saenz Julienne
2019-09-24 18:12 ` [PATCH 05/11] of: expose __of_get_dma_parent() to OF subsystem Nicolas Saenz Julienne
2019-09-24 18:12 ` [PATCH 06/11] of: address: use parent OF node in of_dma_get_range() Nicolas Saenz Julienne
2019-09-24 18:12 ` [PATCH 07/11] dts: arm64: layerscape: add dma-ranges property to qoric-mc node Nicolas Saenz Julienne
2019-10-14 8:28 ` Shawn Guo
2019-10-14 10:00 ` Nicolas Saenz Julienne
2019-10-14 11:09 ` Shawn Guo
2019-09-24 18:12 ` [PATCH 08/11] dts: arm64: layerscape: add dma-ranges property to pcie nodes Nicolas Saenz Julienne
2019-10-14 8:29 ` Shawn Guo
2019-09-24 18:12 ` [PATCH 09/11] of: device: remove comment in of_dma_configure() Nicolas Saenz Julienne
2019-09-24 18:12 ` [PATCH 10/11] of: device: introduce of_dma_configure_parent() Nicolas Saenz Julienne
2019-09-24 18:12 ` [PATCH 11/11] of: simplify of_dma_config()'s arguments Nicolas Saenz Julienne
2019-09-24 21:59 ` [PATCH 00/11] of: Fix DMA configuration for non-DT masters Rob Herring
2019-09-25 14:52 ` Nicolas Saenz Julienne
2019-09-25 15:09 ` Robin Murphy [this message]
2019-09-25 15:30 ` Nicolas Saenz Julienne
2019-09-25 16:16 ` Rob Herring
2019-09-25 16:52 ` Robin Murphy
2019-09-25 21:33 ` Rob Herring
2019-09-26 10:44 ` Nicolas Saenz Julienne
2019-09-26 11:20 ` Robin Murphy
2019-10-02 18:28 ` Florian Fainelli
2019-09-25 16:07 ` Rob Herring
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