From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: hch@lst.de, m.szyprowski@samsung.com,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
noring@nocrew.org, JuergenUrban@gmx.de
Subject: Re: [PATCH] dma-mapping: Relax warnings for per-device areas
Date: Thu, 5 Jul 2018 21:36:13 +0200 [thread overview]
Message-ID: <20180705193613.GA28905@lst.de> (raw)
In-Reply-To: <1f8262d206c6886072d04cc93454f6e3f812bd20.1530623284.git.robin.murphy@arm.com>
> - BUG_ON(!ops);
> - WARN_ON_ONCE(dev && !dev->coherent_dma_mask);
> -
> if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr))
> return cpu_addr;
>
> + BUG_ON(!ops);
> + WARN_ON_ONCE(dev && !dev->coherent_dma_mask);
I think doing dma on a device without ops is completely broken no matter
what you think of it, so I very much disagree with that part of the change.
Also while I don't think not having a dma mask is a good idea even for
a driver purely using dma coherent pools. If the pools really are on
the device itself I can see why it might not matter, but for the case
commonly used on some ARM SOCs where we just reserve memory for certain
devices from a system pool it very much does matter.
There really is no good excuse to not set a coherent mask in the drivers.
next prev parent reply other threads:[~2018-07-05 19:35 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-03 13:08 [PATCH] dma-mapping: Relax warnings for per-device areas Robin Murphy
2018-07-03 16:47 ` Fredrik Noring
2018-07-05 19:36 ` Christoph Hellwig [this message]
2018-07-06 11:57 ` Robin Murphy
2018-07-06 14:19 ` Fredrik Noring
2018-07-06 16:46 ` Robin Murphy
2018-07-06 20:54 ` Fredrik Noring
2018-07-06 23:35 ` Aw: " "Jürgen Urban"
2018-07-07 6:32 ` Fredrik Noring
2018-07-08 20:47 ` Aw: " "Jürgen Urban"
2018-07-15 12:28 ` Fredrik Noring
2018-07-17 14:57 ` Christoph Hellwig
2018-07-17 16:33 ` Fredrik Noring
2018-07-18 21:55 ` Geoff Levand
2018-07-19 13:16 ` 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=20180705193613.GA28905@lst.de \
--to=hch@lst.de \
--cc=JuergenUrban@gmx.de \
--cc=iommu@lists.linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=m.szyprowski@samsung.com \
--cc=noring@nocrew.org \
--cc=robin.murphy@arm.com \
/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