From: Rob Herring <robh@kernel.org>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: devicetree@vger.kernel.org,
Florian Fainelli <f.fainelli@gmail.com>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Arnd Bergmann <arnd@arndb.de>, PCI <linux-pci@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
Marek Vasut <marek.vasut@gmail.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Oza Pawandeep <oza.oza@broadcom.com>,
Stefan Wahren <wahrenst@gmx.net>,
Simon Horman <horms+renesas@verge.net.au>,
Frank Rowand <frowand.list@gmail.com>,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH 05/11] of: Ratify of_dma_configure() interface
Date: Thu, 3 Oct 2019 20:53:09 -0500 [thread overview]
Message-ID: <CAL_JsqLo0jtDcCDf5VTc+_grO3fJ1MsDTE8Bj=B0J+eLk3hpZg@mail.gmail.com> (raw)
In-Reply-To: <0557c83bcb781724a284811fef7fdb122039f336.camel@suse.de>
On Tue, Oct 1, 2019 at 10:43 AM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> wrote:
>
> On Mon, 2019-09-30 at 16:24 -0500, Rob Herring wrote:
> > On Mon, Sep 30, 2019 at 8:32 AM Nicolas Saenz Julienne
> > <nsaenzjulienne@suse.de> wrote:
> > > On Mon, 2019-09-30 at 05:57 -0700, Christoph Hellwig wrote:
> > > > On Thu, Sep 26, 2019 at 07:24:49PM -0500, Rob Herring wrote:
> > > > > -int of_dma_configure(struct device *dev, struct device_node *np, bool
> > > > > force_dma)
> > > > > +int of_dma_configure(struct device *dev, struct device_node *parent,
> > > > > bool
> > > > > force_dma)
> > > >
> > > > This creates a > 80 char line.
> > > >
> > > > > {
> > > > > u64 dma_addr, paddr, size = 0;
> > > > > int ret;
> > > > > bool coherent;
> > > > > unsigned long offset;
> > > > > const struct iommu_ops *iommu;
> > > > > + struct device_node *np;
> > > > > u64 mask;
> > > > >
> > > > > + np = dev->of_node;
> > > > > + if (!np)
> > > > > + np = parent;
> > > > > + if (!np)
> > > > > + return -ENODEV;
> > > >
> > > > I have to say I find the older calling convention simpler to understand.
> > > > If we want to enforce the invariant I'd rather do that explicitly:
> > > >
> > > > if (dev->of_node && np != dev->of_node)
> > > > return -EINVAL;
> > >
> > > As is, this would break Freescale Layerscape fsl-mc bus' dma_configure():
> >
> > This may break PCI too for devices that have a DT node.
> >
> > > static int fsl_mc_dma_configure(struct device *dev)
> > > {
> > > struct device *dma_dev = dev;
> > >
> > > while (dev_is_fsl_mc(dma_dev))
> > > dma_dev = dma_dev->parent;
> > >
> > > return of_dma_configure(dev, dma_dev->of_node, 0);
> > > }
> > >
> > > But I think that with this series, given the fact that we now treat the lack
> > > of
> > > dma-ranges as a 1:1 mapping instead of an error, we could rewrite the
> > > function
> > > like this:
> >
> > Now, I'm reconsidering allowing this abuse... It's better if the code
> > which understands the bus structure in DT for a specific bus passes in
> > the right thing. Maybe I should go back to Robin's version (below).
> > OTOH, the existing assumption that 'dma-ranges' was in the immediate
> > parent was an assumption on the bus structure which maybe doesn't
> > always apply.
> >
> > diff --git a/drivers/of/device.c b/drivers/of/device.c
> > index a45261e21144..6951450bb8f3 100644
> > --- a/drivers/of/device.c
> > +++ b/drivers/of/device.c
> > @@ -98,12 +98,15 @@ int of_dma_configure(struct device *dev, struct
> > device_node *parent, bool force_
> > u64 mask;
> >
> > np = dev->of_node;
> > - if (!np)
> > - np = parent;
> > + if (np)
> > + parent = of_get_dma_parent(np);
> > + else
> > + np = of_node_get(parent);
> > if (!np)
> > return -ENODEV;
> >
> > - ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
> > + ret = of_dma_get_range(parent, &dma_addr, &paddr, &size);
> > + of_node_put(parent);
> > if (ret < 0) {
> > /*
> > * For legacy reasons, we have to assume some devices need
>
> I spent some time thinking about your comments and researching. I came to the
> realization that both these solutions break the usage in
> drivers/gpu/drm/sun4i/sun4i_backend.c:805. In that specific case both
> 'dev->of_node' and 'parent' exist yet the device receiving the configuration
> and 'parent' aren't related in any way.
I knew there was some reason I didn't like those virtual DT nodes...
That does seem to be the oddest case. Several of the others are just
non-DT child platform devices. Perhaps we need a "copy the DMA config
from another struct device (or parent struct device)" function to
avoid using a DT function on a non-DT device.
> IOW we can't just use 'dev->of_node' as a starting point to walk upwards the
> tree. We always have to respect whatever DT node the bus provided, and start
> there. This clashes with the current solutions, as they are based on the fact
> that we can use dev->of_node when present.
Yes, you are right.
> My guess at this point, if we're forced to honor that behaviour, is that we
> have to create a new API for the PCI use case. Something the likes of
> of_dma_configure_parent().
I think of_dma_configure just has to work with the device_node of
either the device or the device parent and dev->of_node is never used
unless the caller sets it.
Rob
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-10-04 1:53 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-27 0:24 [PATCH 00/11] of: dma-ranges fixes and improvements Rob Herring
2019-09-27 0:24 ` [PATCH 01/11] of: Remove unused of_find_matching_node_by_address() Rob Herring
2019-09-27 9:17 ` Geert Uytterhoeven
2019-09-30 12:49 ` Christoph Hellwig
2019-09-27 0:24 ` [PATCH 02/11] of: Make of_dma_get_range() private Rob Herring
2019-09-27 9:18 ` Geert Uytterhoeven
2019-09-30 12:53 ` Christoph Hellwig
2019-09-27 0:24 ` [PATCH 03/11] of: address: Report of_dma_get_range() errors meaningfully Rob Herring
2019-09-27 9:15 ` Geert Uytterhoeven
2019-09-30 12:54 ` Christoph Hellwig
2019-09-27 0:24 ` [PATCH 04/11] of/unittest: Add dma-ranges address translation tests Rob Herring
2019-09-27 0:24 ` [PATCH 05/11] of: Ratify of_dma_configure() interface Rob Herring
2019-09-30 12:57 ` Christoph Hellwig
2019-09-30 13:32 ` Nicolas Saenz Julienne
2019-09-30 21:24 ` Rob Herring
2019-10-01 15:43 ` Nicolas Saenz Julienne
2019-10-04 1:53 ` Rob Herring [this message]
2019-10-07 17:51 ` Nicolas Saenz Julienne
2019-09-27 0:24 ` [PATCH 06/11] of/address: Introduce of_get_next_dma_parent() helper Rob Herring
2019-09-27 9:24 ` Geert Uytterhoeven
2019-09-27 0:24 ` [PATCH 07/11] of: address: Follow DMA parent for "dma-coherent" Rob Herring
2019-09-27 0:24 ` [PATCH 08/11] of: Factor out #{addr,size}-cells parsing Rob Herring
2019-09-27 9:27 ` Geert Uytterhoeven
2019-09-27 0:24 ` [PATCH 09/11] of: Make of_dma_get_range() work on bus nodes Rob Herring
2019-09-27 0:24 ` [PATCH 10/11] of/address: Translate 'dma-ranges' for parent nodes missing 'dma-ranges' Rob Herring
2019-09-27 0:24 ` [PATCH 11/11] of/address: Fix of_pci_range_parser_one translation of DMA addresses Rob Herring
2019-09-29 11:16 ` [PATCH 00/11] of: dma-ranges fixes and improvements Arnd Bergmann
2019-09-30 8:20 ` Christoph Hellwig
2019-09-30 8:56 ` Thierry Reding
2019-09-30 9:55 ` Robin Murphy
2019-09-30 13:35 ` Thierry Reding
2019-09-30 9:20 ` Nicolas Saenz Julienne
2019-09-30 12:40 ` Marek Vasut
2019-09-30 12:52 ` Robin Murphy
2019-09-30 12:54 ` Marek Vasut
2019-09-30 13:05 ` Robin Murphy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAL_JsqLo0jtDcCDf5VTc+_grO3fJ1MsDTE8Bj=B0J+eLk3hpZg@mail.gmail.com' \
--to=robh@kernel.org \
--cc=arnd@arndb.de \
--cc=devicetree@vger.kernel.org \
--cc=f.fainelli@gmail.com \
--cc=frowand.list@gmail.com \
--cc=geert+renesas@glider.be \
--cc=hch@infradead.org \
--cc=horms+renesas@verge.net.au \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=lorenzo.pieralisi@arm.com \
--cc=marek.vasut@gmail.com \
--cc=nsaenzjulienne@suse.de \
--cc=oza.oza@broadcom.com \
--cc=robin.murphy@arm.com \
--cc=wahrenst@gmx.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).