From: Christoph Hellwig <hch@infradead.org>
To: Alexander Lobakin <alobakin@pm.me>
Cc: Ohad Ben-Cohen <ohad@wizery.com>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Arnd Bergmann <arnd@arndb.de>, Amit Shah <amit@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Arnaud Pouliquen <arnaud.pouliquen@st.com>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Christoph Hellwig <hch@infradead.org>,
linux-remoteproc@vger.kernel.org, Suman Anna <s-anna@ti.com>,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH virtio] virtio: virtio_console: fix DMA memory allocation for rproc serial
Date: Mon, 16 Nov 2020 16:30:22 +0000 [thread overview]
Message-ID: <20201116163022.GC16619@infradead.org> (raw)
In-Reply-To: <u9RJBckNwnezQttAPrOyEqDYKu0rnhedUZYGpaS83qg@cp3-web-024.plabs.ch>
On Mon, Nov 16, 2020 at 01:07:28PM +0000, Alexander Lobakin wrote:
> But lots of subsystems like netdev for example uses dev->parent for
> DMA operations. I know that their pointers go directly to the
> platform/PCI/etc. device, but still.
Oh, every drivers is perfectly fine to use ->parent as it suits. The
problem is when we have layered architectures, where this pokes a
massive hole into the layering.
> The only reason behind "fake" DMA devices for rproc is to be able to
> reserve DMA memory through the Device Tree exclusively for only one
> virtio dev like virtio_console or virtio_rpmsg_bus. That's why
> they are present, are coercing DMA caps from physical dev
> representor, and why questinable dma_declare_coherent_memory()
> is still here and doesn't allow to build rproc core as a module.
> I agree that this is not the best model obviously, and we should take
> a look at it.
As far as I can tell the series from Arnaud does the right thing here.
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prev parent reply other threads:[~2020-11-16 16:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <AOKowLclCbOCKxyiJ71WeNyuAAj2q8EUtxrXbyky5E@cp7-web-042.plabs.ch>
2020-11-05 3:10 ` [PATCH virtio] virtio: virtio_console: fix DMA memory allocation for rproc serial Jason Wang
[not found] ` <aXBO8lWEART2MNuWacIKln3qh6wttCtF2oUd7vthkNU@cp3-web-012.plabs.ch>
2020-11-09 6:04 ` Jason Wang
2020-11-16 9:19 ` Christoph Hellwig
2020-11-16 9:51 ` Michael S. Tsirkin
2020-11-16 16:27 ` Christoph Hellwig
2020-11-16 10:46 ` Arnaud POULIQUEN
2020-11-16 16:28 ` Christoph Hellwig
2020-11-16 16:39 ` Christoph Hellwig
2020-11-17 14:00 ` Arnaud POULIQUEN
2020-11-17 14:02 ` Christoph Hellwig
2020-11-18 10:16 ` Michael S. Tsirkin
2020-11-16 12:25 ` Michael S. Tsirkin
[not found] ` <u9RJBckNwnezQttAPrOyEqDYKu0rnhedUZYGpaS83qg@cp3-web-024.plabs.ch>
2020-11-16 13:12 ` Michael S. Tsirkin
2020-11-16 16:30 ` Christoph Hellwig [this message]
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