From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Phil Elwell <phil@raspberrypi.com>,
Stefan Wahren <wahrenst@gmx.net>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Christoph Hellwig <hch@lst.de>,
Florian Fainelli <florian.fainelli@broadcom.com>,
Robin Murphy <robin.murphy@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
linux-staging@lists.linux.dev
Subject: Re: WARNING: drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:364 vchiq_prepare_bulk_data
Date: Mon, 10 Jun 2024 12:15:34 +0300 [thread overview]
Message-ID: <20240610091534.GO18479@pendragon.ideasonboard.com> (raw)
In-Reply-To: <72a414e4-4cd0-4b12-a662-cb73d1e3515e@app.fastmail.com>
On Mon, Jun 10, 2024 at 11:00:12AM +0200, Arnd Bergmann wrote:
> On Mon, Jun 10, 2024, at 10:26, Phil Elwell wrote:
> > On Mon, 10 Jun 2024 at 07:00, Arnd Bergmann <arnd@arndb.de> wrote:
> >
> > Why is swiotlb involved at all? The DMA controller on BCM2837 can
> > access all RAM that is visible to the ARM cores.
>
> When a device is not cache-coherent and the buffer is not
> cache aligned, we now use swiotlb to avoid clobbering data
> in the same cache line during DMA synchronization.
>
> We used to rely on kmalloc() returning buffers that are
> cacheline aligned, but that was very expensive.
Could we reject buffers provided by userspace that are not cache-aligned
?
--
Regards,
Laurent Pinchart
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next prev parent reply other threads:[~2024-06-10 9:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-09 22:24 WARNING: drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:364 vchiq_prepare_bulk_data Stefan Wahren
2024-06-10 6:00 ` Arnd Bergmann
2024-06-10 8:26 ` Phil Elwell
2024-06-10 9:00 ` Arnd Bergmann
2024-06-10 9:15 ` Laurent Pinchart [this message]
2024-06-10 9:19 ` Arnd Bergmann
2024-06-10 9:24 ` Phil Elwell
2024-06-10 10:09 ` Arnd Bergmann
2024-06-10 10:25 ` Robin Murphy
2024-06-11 10:47 ` Stefan Wahren
2024-06-11 11:08 ` Arnd Bergmann
2024-06-11 11:37 ` Stefan Wahren
2024-06-11 12:14 ` Arnd Bergmann
2024-06-11 13:09 ` Stefan Wahren
2024-06-11 13:35 ` Robin Murphy
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