From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: phill@raspberryi.org, devicetree@vger.kernel.org,
f.fainelli@gmail.com, linux-mm@kvack.org, marc.zyngier@arm.com,
Will Deacon <will@kernel.org>,
linux-kernel@vger.kernel.org, eric@anholt.net,
iommu@lists.linux-foundation.org, robh+dt@kernel.org,
linux-rpi-kernel@lists.infradead.org, mbrugger@suse.com,
Robin Murphy <robin.murphy@arm.com>,
akpm@linux-foundation.org, frowand.list@gmail.com, hch@lst.de,
linux-arm-kernel@lists.infradead.org, wahrenst@gmx.net
Subject: Re: [PATCH 5/8] arm64: use ZONE_DMA on DMA addressing limited devices
Date: Thu, 01 Aug 2019 17:44:09 +0200 [thread overview]
Message-ID: <d8b4a7cb9c06824ca88a0602a5bf38b6324b43c0.camel@suse.de> (raw)
In-Reply-To: <20190731170742.GC17773@arrakis.emea.arm.com>
[-- Attachment #1.1: Type: text/plain, Size: 1734 bytes --]
On Wed, 2019-07-31 at 18:07 +0100, Catalin Marinas wrote:
> On Wed, Jul 31, 2019 at 05:47:48PM +0200, Nicolas Saenz Julienne wrote:
> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> > index 1c4ffabbe1cb..f5279ef85756 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -50,6 +50,13 @@
> > s64 memstart_addr __ro_after_init = -1;
> > EXPORT_SYMBOL(memstart_addr);
> >
> > +/*
> > + * We might create both a ZONE_DMA and ZONE_DMA32. ZONE_DMA is needed if
> > there
> > + * are periferals unable to address the first naturally aligned 4GB of ram.
> > + * ZONE_DMA32 will be expanded to cover the rest of that memory. If such
> > + * limitations doesn't exist only ZONE_DMA32 is created.
> > + */
>
> Shouldn't we instead only create ZONE_DMA to cover the whole 32-bit
> range and leave ZONE_DMA32 empty? Can__GFP_DMA allocations fall back
> onto ZONE_DMA32?
Hi Catalin, thanks for the review.
You're right, the GFP_DMA page allocation will fail with a nasty dmesg error if
ZONE_DMA is configured but empty. Unsurprisingly the opposite situation is fine
(GFP_DMA32 with an empty ZONE_DMA32).
I switched to the scheme you're suggesting for the next version of the series.
The comment will be something the likes of this:
/*
* We create both a ZONE_DMA and ZONE_DMA32. ZONE_DMA's size is decided based
* on whether the SoC's peripherals are able to address the first naturally
* aligned 4 GB of ram.
*
* If limited, ZONE_DMA covers that area and ZONE_DMA32 the rest of that 32 bit
* addressable memory.
*
* If not ZONE_DMA is expanded to cover the whole 32 bit addressable memory and
* ZONE_DMA32 is left empty.
*/
Regards,
Nicolas
[-- Attachment #1.2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
[-- Attachment #2: Type: text/plain, Size: 156 bytes --]
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2019-08-01 15:45 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-31 15:47 [PATCH 0/8] Raspberry Pi 4 DMA addressing support Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 1/8] arm64: mm: use arm64_dma_phys_limit instead of calling max_zone_dma_phys() Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 2/8] arm64: rename variables used to calculate ZONE_DMA32's size Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 3/8] of/fdt: add function to get the SoC wide DMA addressable memory size Nicolas Saenz Julienne
2019-08-02 17:17 ` Rob Herring
2019-08-05 16:03 ` Nicolas Saenz Julienne
2019-08-05 19:23 ` Rob Herring
2019-08-06 18:12 ` Nicolas Saenz Julienne
2019-08-08 15:02 ` Rob Herring
2019-08-08 17:30 ` Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 4/8] arm64: re-introduce max_zone_dma_phys() Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 5/8] arm64: use ZONE_DMA on DMA addressing limited devices Nicolas Saenz Julienne
2019-07-31 17:07 ` Catalin Marinas
2019-08-01 15:44 ` Nicolas Saenz Julienne [this message]
2019-08-01 16:07 ` Robin Murphy
2019-08-01 16:40 ` Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 6/8] dma-direct: turn ARCH_ZONE_DMA_BITS into a variable Nicolas Saenz Julienne
2019-08-01 14:04 ` Christoph Hellwig
2019-08-01 15:59 ` Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 7/8] arm64: update arch_zone_dma_bits to fine tune dma-direct min mask Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 8/8] mm: comment arm64's usage of 'enum zone_type' Nicolas Saenz Julienne
2019-08-01 14:08 ` Christoph Hellwig
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=d8b4a7cb9c06824ca88a0602a5bf38b6324b43c0.camel@suse.de \
--to=nsaenzjulienne@suse.de \
--cc=akpm@linux-foundation.org \
--cc=catalin.marinas@arm.com \
--cc=devicetree@vger.kernel.org \
--cc=eric@anholt.net \
--cc=f.fainelli@gmail.com \
--cc=frowand.list@gmail.com \
--cc=hch@lst.de \
--cc=iommu@lists.linux-foundation.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-rpi-kernel@lists.infradead.org \
--cc=marc.zyngier@arm.com \
--cc=mbrugger@suse.com \
--cc=phill@raspberryi.org \
--cc=robh+dt@kernel.org \
--cc=robin.murphy@arm.com \
--cc=wahrenst@gmx.net \
--cc=will@kernel.org \
/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).