From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
To: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
Cc: noring-zgYzP9v7iJcdnm+yROfE0A@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
JuergenUrban-Mmb7MZpHnFY@public.gmane.org,
hch-jcswGhMUV9g@public.gmane.org
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-5wv7dgnIgG8@public.gmane.org>
> - 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 19:36 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
[not found] ` <1f8262d206c6886072d04cc93454f6e3f812bd20.1530623284.git.robin.murphy-5wv7dgnIgG8@public.gmane.org>
2018-07-03 16:47 ` Fredrik Noring
2018-07-05 19:36 ` Christoph Hellwig [this message]
[not found] ` <20180705193613.GA28905-jcswGhMUV9g@public.gmane.org>
2018-07-06 11:57 ` Robin Murphy
[not found] ` <5811ebe5-b2bd-efc1-bf54-a8f05432c4f8-5wv7dgnIgG8@public.gmane.org>
2018-07-06 14:19 ` Fredrik Noring
[not found] ` <20180706141926.GA2313-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2018-07-06 16:46 ` Robin Murphy
[not found] ` <bd63815c-260e-078f-4184-561c8e54e636-5wv7dgnIgG8@public.gmane.org>
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
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