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From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: 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>,
	Robin Murphy <robin.murphy@arm.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 16:52:59 +0200
Message-ID: <d1a31a2ec8eb2f226b1fb41f6c24ffb47c3bf7c7.camel@suse.de> (raw)
In-Reply-To: <CAL_Jsq+v+svTyna7UzQdRVqfNc5Z_bgWzxNRXv7-Wqv3NwDu2g@mail.gmail.com>

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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.

Also I tested your branch both on an RPi4, with a PCI device that depends on
these changes and by comparing the OF debugs logs on a Layerscape board which
uses dma-ranges, dma-coherent and IOMMU. All works as expected.

Will you send this series for v5.5? Please keep me in the loop, I'll review and
test the final version.

Regards,
Nicolas


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From 26d51853c25c04c28dbc09061951a93c102dabcd Mon Sep 17 00:00:00 2001
From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Date: Wed, 25 Sep 2019 16:26:57 +0200
Subject: [PATCH] of: device: do not bail of_dma_configure() when force_dma is
 set

Some Xen devices call of_dma_configure() without an actual DT node in
order for it to set its 'dma_ops'. That's the original intent of
'force_dma', honor that behaviour.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/of/device.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index a45261e21144..7bc00f72468f 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -100,8 +100,6 @@ int of_dma_configure(struct device *dev, struct device_node *parent, bool force_
 	np = dev->of_node;
 	if (!np)
 		np = parent;
-	if (!np)
-		return -ENODEV;
 
 	ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
 	if (ret < 0) {
-- 
2.23.0


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  reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-24 18:12 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 [this message]
2019-09-25 15:09     ` Robin Murphy
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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